Do you get a notification when you receive a warning? It should be in the form of a DM/PM with a link to the post. That might be the best time to contest a warning.
In general I think warnings should be reserved for egregious violations of the rules. I myself have pulled back on a lot of warnings. At times I've personally been guilty of overreacting and losing my temper on certain posts and issuing warnings. I've also gone back later and reversed warnings in many cases where I realized I wasn't acting objectively, so it's absolutely not a perfect system and open to abuse.
For example, I don't issue warnings for 'trolling' anymore - just delete the post and thread ban the member if necessary.
We can definitely do that. How?
Why have time durations for warnings? It's not like an offense gets less offensive after tge passage of time.
If you get x offense (say 5 not 3), regardless of how much time has accrued, you get a week off.
But, then you should consider the double and triple jeopardy thing, as those offenses already resulted in a punishment, so should not cause the offender to be punished once more for the same offense.
So on a ban, the cumulative offenses lapse, and when the member comes back he starts with a new slate.
I think guys like you who have been across most forums over the years knows that every forum has a resident vibe, and a particular demographic.
PDF has always been about free flowing debate.
It's never going to be a tech forum.
It's never going to be a strategy forum with actual vets.
It's a forum for bored white collar geeks who want to poke the other side.
Question is, what are you guys trying to do with it ...