Another good question. It depends. If you nurture bad feelings, they become a part of you, which, in my opinion, is not healthy. Fully repressing negative emotions is not healthy either as, again, these feelings become a part of you, but will also surface at some point. I guess it is about time and place. And duration.
If you get angry or upset in a situation where showing that emotion and/or giving in to it would be detrimental, then yes, surprise until a later time! Ideally later that same day. This could be an important business meeting where your manager throws you under the bus. It won’t help you to give in to your emotions there and then (there are clients present!). Giving in may also result into words/actions that you may regret later, but then cannot take back anymore.
Does this mean you just have to roll over and let your boss get away with crap? Of course not. Feel your feels without an audience. Process them. Is it a really bad situation that you cannot process completely that same day? Then take more time! It may also sometimes help to agree with yourself how much time you will take. Next, when you can think clearly and with less emotion, go talk with your boss (or whoever upset you). There are ways to have this conversation without the other party getting upset right back at you. Mind you though, you cannot control how the other person reacts to what you have to say!
I once had a situation where my manager told me that I wasn’t doing a good job (I did not know at the time that he was told by higher up to tell me this), and I knew it was a load of crap. It took me a several days and several venting sessions with co-workers and friends to calm down enough to think. By that time, my boss asked me whether we could talk and I told him that we will, but when I was ready. I then needed several more days to think things over and come up with what I wanted to say to my boss and how. Finally after 2 weeks or so, I sat down with my manager and shared my thoughts and views and ended up having a very good conversation with him, during which he confided in me that he was told to do this, but absolutely did not agree. Obviously, this was an ideal outcome, which is not always going to be the case.