The same tactics used in game development against cheaters. If it would ban you right after prompt you'll know how to avoid getting banned.
Obviously that didn't worked for you because you wasn't doing multiple attempts to bypass filters like if you were jailbreaking it by repeatedly trying different stuff.
One of my friends in high school used to cheat on a popular video game. The fact ban waves would occur about once a week to once a month meant whenever his accounts got banned, he never knew why exactly and wasn't able to stop it the next time.
Of course, if ban waves are too long apart then yeah you're just letting a known cheater wreak havoc on the playerbase.