You can twit as much as you want to twit. If people are following you it must be because they like what you post
I don't see any problem with more than 10 twits a day. As long as they're actual twits and not spam of course.
The dozen auto-tweets from an rss feed posted all at once gets annoying even if they're interesting. If they're spread out overthe course of the day, fine.
At least 100 twits per day? Wow, you must have Twitter on your phone! There's only 24 hours a day, you need at least 4 interesting stuff happening every hours and that's the MINIMUM?
Actually I can see that. We have a twitter account that's used for server monitoring. We did contact the twitter folks first and ok it via them.