When milestones are set each month, then its okay. I made the experience, though, that as long as the development proceeds, the milestones get lighter each time they are closed. Especially the bug to feature ratio grows from 0 at the beginning very fast during development.

In fact, sometimes you have to cut down the whole feature-lineup to the half to be ready for the final deadline because you have such a big list of bugs and final improvements you have to made. Its not the pressure behind me that makes me worse but stupid publishers which say "ok lets pull the deadline 1 or 2 months so that we can get our money a bit earlier"... man! I hate that, because my personal degree of perfectionism and quality cannot be fulfilled, but this is a very common way most publishers go, so I don't worry at all. I tell myself "hey, I could have done it better, but they didnt let me"

ahh and by the way: Game development is only 10% fun. Seriously. So, .. ... we hate fun.

Regards
Christian