Taking on a lot of games can be a little overwhelming (I had about 90 going last month). It all depends on the time you have in your life. It's frustrating to feel that you're rushing the clock and need to make moves in ten games before bedtime so you don't time out, but then realize the next day that you weren't thinking straight because you were too tired :-)
If you suddenly sign up for a whole bunch, and there are a few weaker players in the pool, you might also find that you will win a bunch of the easy ones quickly, resulting in a quick boost to your rating, but that's only temporary - once you start losing those games you deserve to, it will drop back down. If you want your rating to reflect your strength (i.e. you're not trying to "game" the number), be honest with yourself and resign at an appropriate point rather than trying to drag the losing games on - that will limit this false rating spike.
Figure out how much time you think you need or want to spend on an average move, figure out your time-life budget per day, and make sure you're in line with the math. I set an egg timer for 5 minutes each move to try to prevent myself from moving too fast and making obvious blunders - otherwise I'm too tempted to play like it's a 5|0 game. At 5 minutes per move, and an hour a day, you could easily handle 12 games/day; or 36 three-day games. Of course a few games always have obvious exchanges that don't need the full time but there are others that take more, so the average is about right for me.
Good luck!
I just blocked ilikeflags so he won't be commenting here anymore. At least I think that is how it works