While most reasonably mature and well adjusted people have many things in common, there are, I think, very few things that "we all do". There are some, of course. We all have a certain number of basic body functions that "we all do". Also, I think it's reasonably safe (even though I'm still being cautious here) to say that we all, or at least most of us, make one kind of mistake or another. That may be something like, for example, some of the stupid things children and teens may do because they're either too young to know better (or wiser), young enough that they're at an impulse control stage, or are at an age when they don't have enough information/perspective. Also, children and young people often listen to the wrong people.
While most (certainly not all) children or teens outgrow some of the aspects of their age that are the major contributors to what are often (certainly not always) foolish mistakes, plenty of people keep a certain degree of immaturity (sometimes throughout their whole life, more often perhaps, until they pick up some life experience) well beyond reaching maturity. They make mistakes for the same reasons kids do - they don't know any better.
For adults with some experience, common sense, awareness, and a reasonable degree of understanding/balance; mistakes can more often be of the type that involves making choices based on not having a crystal ball and/or not having (sometimes through no fault of one's own) enough information.
And while some people are better than others as managing their own emotions, there will probably always be people who make mistakes that are colored by emotions. Of course, emotions generally involved relationships, so the more relationships someone has, and the longer that person has them, probably puts him at higher risks for "emotion-based" mistakes. The flip side of that, though, is that the more relationships one has, and the longer he has them, also means picking up a little understanding and/or wisdom as well. (Good thing, too, because understanding and wisdom can help in addressing some of those mistakes one has made as a result of being fortunate enough to have lots of close relationships for long periods of time.)
In any case, other than body functions and mistakes, I can't really think of too many (any) things that "we ALL DO", because we're all different. We're all individuals. We can have lots of things in common, but when it comes to most things (the things that differentiate our personalities, our personal history, and/or our individuality), it's probably wiser and most accurate (when we're referring to one thing or another) to either say "\many of us do" or "some of us do". That is if we're truly interested in being accurate.
Here's the thing about the phrase, "we all do": Sometimes someone who says that is harmless. He's just someone who is too careless with words and isn't all that concerned about accuracy. The thing is, however, should we be listening to the person who isn't too concerned with accuracy? I say, if othing else, think twice about someone so unconcerned with accuracy.
I don't imagine that I'm the only person in the world who has, time
and time again, read or heard "we all do" and thought, "well, I don't".
Sometimes people say or write, "we all do", not because they really believe that "we all do" (because they know that, in fact, they "don't"). They're just trying to find something to say to those people who9 "do" in order not to seem self-righteous, arrogant, and/or superior. They mean well, but it's a lie (and a condescending one to boot). This goes back to the thing about the lack of wisdom in listening to someone who isn't worried about the truth. Also, it's out-and-out wrong to allow, or lead, people to think "we all do" when, in fact, "we all don't".
Someone else who says or writes, "we all do", are people who have products/services to sell and who don't want to be off-putting to those to whom the products/services are aimed.
Sometimes, however, someone isn't selling something. He just says (even thinks), "we all do" because it's common for people to think that they because they "do" something or "are" something that everyone else must be like they are. With negative traits or behaviors people often make themselves feel better by believing that "we all do" (when "we all don't"). Or else, some people may simply believe "we all do" because they listened to someone else who told them that "we all do". People often do the same thing with positive traits. Sometimes they'll realize that they could be wrong in assuming that everyone else is like they are. Sometimes they don't. Sometimes they learn better. The point is that it's not very easy to come up with things (other than what I've mentioned above) that "we ALL do". I can think of a few examples: There's the lie out there that "we all do" have a favorite child". Anyone who knows has enough children (and maybe enough children long enough) and who knows that one's a lie knows for certain that it's a lie. Plain and simple. I'm not saying that SOME people don't have a favorite child. Obviously, all those people who think "we all do" will tell you otherwise. In fact, if you try to argue with them they'll dig in their heels in order to hang onto their own belief. That's not the point, though.
Another one is of the "we all are" variety, and that one is the one that "we all are jealous" at one time or another (some more often, or more, than others). That's another lie. We all aren't.
Then there's a slightly different type of "we all do", and that's "we all lie". While I have no way of knowing how many people would absolutely, and for no reason, ever lie; my own take on the matter is that it's probably safer and more accurate to say that most of us lie at one time or another, and some people make a bigger habit of it than others. Some people (who are grown up)will try very hard to never, ever, lie to anyone. There may be, however, times even such people may feel forced by circumstances (and sometimes compassion or other trait that conflicts with complete honesty) to try to come up with the least objectionable "light" lie he can. On the other hand, there are people who just throw around all kinds of lies as a way of getting them through the moment or accomplishing whatever else they hope to accomplish (and with as little regard for accuracy and truth as those who are free to throw around "we all do" have). The twist with lies and "we all do" is that maybe most of us "do", but, truly, no all lies are either the same degree of severity or lack-of-integrity. (Those who say they are are, lying (either to themselves or someone else). The point is that lies are a good example of something that many, many, people do; but it's not like saying, "we all breathe".)
My point here (again) is beware those words, "we all do", because in so many, many, instances "we all don't". We just don't. Someone who says "we all do" because he's being condescending doesn't understand you and/or your situation/problem well enough. Doesn't matter. He isn't someone who should be advising you (or others). And, if someone is saying, "we all do", because he does (and he therefore thinks "we all do" because he believes everyone else is just like he is then that person is not recognizing the individuality of people and situations. That may be misguided enough, but worse than that is the person who says/believes, "we all do" because it helps him preserve and/or inflate his own ego (even if that means failing to see, or denying, the truth).
Earlier in the evening I ran into a reasonable enough article that made one mistake, and that was in using those words, "we all do". While the article was fine for those to whom it applied, it, like most of all those other instances when someone writes/says, "we all do", could have been better if it had left off "we all do", let those who agreed and believed the article had things right enjoy the article, and leave room for those who realized that the article did not apply to them simply move on, find another article that seemed to apply more, and not come away being acutely aware of yet one more instance in which someone said, "we all do" about something that someone else knows, without doubt,that we ALL don't".
After all, while it's harmless enough for someone to say "we all do" when discussing something like enjoying sewing one 's own curtains (which, of course, we certainly "all DON'T"), "we all do" is often used when things like self-esteem, ego, the need for appropriate guidance (or at least the need to feel understood in some situations) or just the need/desire for truth/accuracy are particularly important to the person for whom "we all do" isn't just not the truth but may be, at least in some ways, harmful/hurtful.
It's probably reasonably safe and accurate to say that the difference between "flawlessly credible" and "clearly questionable (at least to someone who knows better)" can be those words, "we all do" and on whether the person speaking/writing knows enough not to use them.