I disagree with 15 minutes being too much. Anyone can write an answer in less than fifteen minutes, but will it be a good one? The following takes most certainly more time than 15 minutes:
- reading the question thouroughly, understanding the problem
- doing on-site research (other answers, should it be closed as duplicate instead?)
- doing external research
- write an answer good for, both, asker and others
- proofreading that answer for mistakes
One could even see answer time as an indirect quality measurement. I don’t think good expert-volunteers will ever hit this threshold, and for all others: is this really bad?
Nope. I meant, that if your “bad” content is less than one-fifth of your overall content, the automatic system doesn’t kick in. Instead a moderator reviews your behavior and acts appropriately (inc. possible suspension)
For all people, where the bad contribution makes up a high amount of their content (more than 1/5), the automatic system kicks in. Possibly also raising moderator flags, but with lower priority.
Example:
3 times Offensive, 20 posts → 15% → moderator flag
3 times Offensive, 10 posts → 30% → downleveled
10 times Offensive, 20 posts → 50% → downleveled
All this only applies to offensive, not to spam.