I've many times bumped up unanswered questions by improving them with edits, and found that they got answered shortly after, so this was indeed helpful. However this time I did 16 questions at once:
Is it beyond the point where it would be optimally helpful? If I were to bump up 5 or 6 questions like this, I'm sure most users would see the 5/6 questions newly at the top of the list and read all titles, but if 200 questions newly appeared at the top of the list, no user would read all the titles (and therefore some of the newly bumped questions appearing towards the end, would not be seen and would therefore not get answers, making the bump-up a waste). So perhaps somewhere between 5 and 200 would be appropriate, but would 16 be too much?
I suppose we'll see what happens (i.e. which questions get answered this time, if any, and which ones get ignored, if any). The reason I did 16 this time was because I wanted to do a bump-up drive back in mid-July followed by another one in mid-August (6 months after the January bump-up and the February bump-up), but then someone else bumped up a bunch of answered questions already, which bumped-down a lot of the newly asked unanswered questions, so bumping-up even more on top of that would seem sub-optimal).