For an online community, Facebook has the most least understand and least organized set of rules to guide people around on Facebook on what is allowed, and what is not. Because of that, it seems to be impossible for users of Facebook to know when they are breaking the rules and when they are not.
Here is a set of Facebook rules that are loose, and could in theory last forever for no reason at all.
http://www.facebook.com/help/?page=1048
From rule: I have been blocked from using a feature.
Unfortunately, Facebook cannot provide any specifics on the rate limits that are enforced. The threshold at which you are warned is not a specific number, but rather determined by different factors, such as speed, time, and quantity.
From rule: I have been blocked from sending messages.
When you are allowed to resume sending messages, keep in mind that it’s possible to run into a block based on how many messages you send and how fast you send them. It’s also possible to be blocked when either starting a new message thread or replying to a message. Lastly, deleting old messages will not allow you to send more messages. In the future, please proceed with caution to avoid hitting the limit again. Please be aware that further abuse of such features can result in your account being permanently disabled.
From rule: Why didn’t my friend request go through?
If you have been prevented you from adding friends on Facebook, it is likely because many recent friend requests sent from your account have gone unanswered. This may be because you’ve asked strangers to be friends or because you’ve engaged in other behavior that Facebook users have reported as unwelcome. When you are allowed to use this feature again, only send friend requests to people that you already know to avoid having additional limits placed on your account.
From rule: Why is Facebook asking me to confirm my identity by providing my phone number?
This is a security measure to help ensure that Facebook remains a community of people using their real identities to connect and share. If you ever lose your password, you’ll also be able to use your mobile number to access your account.
From rule: What if I didn’t receive a warning before becoming disabled?
Depending on the severity of the violation, it is not guaranteed that you will receive a warning prior to becoming disabled. Unfortunately, accounts that are disabled for severe violations of Facebook’s Statement of Rights and Responsibilities cannot be restored.
Note that in this rules that in many cases there are no limit sets, not high and low and none is given in the Help pages. So the limit in question is a guess like the next week lottery number. You might hit the limit on a bad day, on a good day you might not hit it at all.
This behavior of Facebook, keeping everything loose and rater ill regulated is there own guide for a failure. It might take three or five more years until the cracks start to appear on Facebook, but in the end they are going to appear and in the end going to be the demise of Facebook.
I don’t trust Facebook, and I don’t recommend that anyone does.