I have been trying to either get an answer from Twitter (never answered) or learn what Twitter's real follow rules are.  I can tell you they've gone from none, to 2000 follows or 120% of your followers number, to 2000 follows or 110% of your followers number, to that rule plus some new blocking mechanism for people that use "unauthorized scripts."

How they determine an unauthorized script, who knows.  Since I'm running my own scripts, on 1 IP, and several accounts using these scripts have been blocked, it seems that any script that doesn't have explicit auhtoization from Twitter would qualify.  They don't clarify this issue.  They disclose even less about their reasons for blocking follows on accounts that aren't over their prescribed follow limit.

One could go with "just don't follow a lot of people."  Or, you could go with "just be reasonable."  But, I can't determine what those are.  I thought following 120 people that were tweeting about dieting was reasonable.  Apparently, it's not.  There are many factors.  Others are using my script (because I share) and may be using it more agressively than me.  Others are using it so maybe we're tagged as sending too much traffic their way.  We just can't know.  They won't tell.

Oddly, I have two accounts (for purely commercial purposes) that don't get blocked, but both are under the infamous 2000 follows number.  I find this truly odd.  I have managed to create follow blocks for two accounts with more than 2000 follows, less follows than followers, so all but the script use seem to comply with their published rules/limits.  However, their rules seem intentionally vague.

The only thing that is clear is that I'm under the follow limit rules and they have definitely blocked my ability to follow new people.

Sure, fair enough.  There are clear rules about how many people I can follow, non-recipricol, etc.  Only how clear is it?  They say "agressive follows" will get you suspended.  Well, this isn't an account suspension it's, just a follow block.  And, they define agressive following in extremely vague terms.  So, last night I picked out about 120 people I'd like to follow and a script to work on it.

I'd love clear guidelines that just tell me the rules, but Twitter's insistance on vague rules (and ever changing rules) force me to just test the limits and see what non-spam behavior will get your account limited.

Clearly, my account is far under the limits.  I'm following fewer people than are following me.  So, I can't be guilty of "following thousands of people that do not reciprocate."  Clearly, it was the automation that has now three times frozen my ability to follow.  And, the magic number is under 200.  So, you don't have to follow that many people to get banned if you've been identified as using some automation service.

What's odd is that I don't see this problem with certain automatic follow services, like follow back services for example, which performs the exact same function.  Since my numbers are so small I can't imagine I've been identified by human eyes as being a problem.  And I predict that once I leave it alone a few days I'll resume follow functionality like normal.

Twitter has never answered my questions about this issue, and I expect they never will.  Bottom line is, don't write scripts to interface with Twitter unless you are fully prepared to have them block them or break them randomly with no published or directly related cause.