05/29/2019 (Wed) 19:20:45
afaik, the flood timeout for anonymizing frontends is about 1 minute per post per board (not just your posts, but all non-IP posts per board) and if anyone breaks this limit the timeout is bumped to several more minutes
the "block bypass" shit is hack around this: it requires cookies and basically "deanonymizes"/individualizes/isolates you by giving you a "bypass token" that allows the board software to track your posts in separation from all other non-IP posters
this "bypass token" has a limited duration (it expires after some hours, I think more than a day) and limited usability (it expires after some number of posts, more than a dozen) and of course if the cookie itself expires or is deleted then you lose the token as well
also, posting with this token bypass is rate-limited as well, but much less severely: I think it's about 30 seconds or less
so, if you have no problem with that, you are supposed to solve the bypass captcha only once per "session"
additionally, some boards may require solving a similar captcha when posting or when creating a new thread
(the captcha image *also* has an expiration timeout but that is a different matter and you probably won't notice if you have javashit enabled)