I’ve been developing web application couple of weeks ago and catch the problem with limit of FQL requests. Facebook just was ignoring my requests and I receiving empty string instead XML. There was two days high transmitting data by FQL: I tried to get info from Facebook by 20-30 requests every 10-30 minutes (by cron job).
Also I didn’t find limits in official documentation about FQL. I don’t know exactly probably issue of this trouble is changed Facebook API and protection from bottle necks in new system but in fact they are ban my application by ip address because there were too many requests.
So be carefull with too many request to Facebook..
Is there any other experience in this area?