As long as you aren't spread across the entire school grounds, I'd say max two rooms at any time, and as long as you aren't messing up the time or anything like that, then yeah it'd be ok if you're in more than one thread at a time.  Just be careful you don't confuse yourself or anything like that.  I'm about to add Lilith's 'classroom' to the list if anyone wants to check it out.  Also, if you guys want to start heading to the Main Hall/Dining Hall thread, I'd appreciate it so that I won't have to repeat myself too many times.  Who wants to go first as far as their class goes while I'm thinking about it?  Just thought I'd ask while I'm rambling away lol.