I am a third year graduate student at a "top-20" university who works on fine-grained complexity (lots of playing with 3-SUM, OV and the usual popular hardness conjectures). I have been fairly productive over the last year or so and have 3 accepted papers and two submitted papers. All of this to say that I am a fairly experienced graduate student and what I am about to describe is not anecdotal.
Every submission brings me more dissatisfaction than satisfaction. Just before I start working on a problem, me and my advisor identify a list of concrete questions that need to be answered. After lots of thinking, we have some very nice non-trivial results which gives me a lot of happiness and satisfaction. As we start to write down all of the results, inevitably, there are some more interesting variants that pop up but are much harder to make progress on. After the initial euphoria point, I feel everything seems to go downhill. There are so many variants that also need to be answered, are clearly in the purview of the problem at hand but I am not able to. By the time we submit the paper, I am so dismayed that results in the paper seem almost trivial. Perhaps this is simply tunnel vision, but I can't overcome the sadness about not being able to answer peripheral questions (although these make for a terrific conclusion section).
This has happened every single time and I am wondering if this is a common feeling. Do other people in theory community feel the same way? I am not sure if this is an academia wide feeling. My fellow graduate students from other areas are over the moon after every submission (but this is just anecdotal).
Edit - I see that there is another soft-question on the front page. I apologize for adding another one. Its holiday season and (only?) after a few drinks, one starts to ponder over these things!