[quote=@Shorticus]
<Snipped quote by vancexentan>

How often does this happen, out of curiosity?

I can see reasons why someone would do that (including just plain forgetting), but I would like to know how often that occurs in case I ever run my own RP.
[/quote]

I find that people that sometimes do this tend to be lacking an RP and they are guaging their interest and others by dropping a post in several rps and seeing which one they'll end up joining. I did this once but that was because of the three that I applied for, one gm got back to the RP after several days, one went a direction that didn't interest me after seeing what the people we're talking about, and the third ended up being a successful RP. 

There's also some members who cannot time manage. So they'll apply and get back to the site several days later and forget about the RP.

There's also a drop off rate once a few people start to enter, so if you're ever going to gm a game, be prepared for that too.