I've seen some behavior from the bounty system that I did not expect, though it couldn't be called official unexpected behavior. One example is this question. I've been working on it for about 3 months, and if I remember correctly I've had at least one bounty on it in the past with no results.
This time I hit gold. I placed a bounty for
+300 and received two excellent answers. I wanted to award points to both. I've learned here that there are anti-gaming measures in SE that have the result that whenever you add a second bounty to a question the number of points must be higher than the first.
Since I'd seen progressions in steps of 50 before, I assumed that the next bounty I could generate would be
+350, but it wasn't. In fact I only had one choice,
+500. So I generated it.
Now there is a third answer that is also potentially bounty-worthy. So I would like to ask ahead of time, in this case is it possible to generate a third bounty, or have I "run out" at two?
What about if I had started lower, would I have had more bounties available and it's only because I've started at
+300 that I've run out?
Why were choices between
+500 no longer available for the second bounty?