What's the difference between PV and PW reset when going too hard on Twitter?

1. What is safe Twitter follow / like settings per hour and per day?
2. I get PV and PW reset randomly few times per month probably cause I am going too hard, when is PV compared to PW reset triggered?

Come on BLACKHATWORLD!

Good settings are
300-1000 per day. Delays between 9-20 seconds with 150 accounts per follow project, and 25 threads running.
This would usually have my accounts following between 400-650 users per day.

Maybe you're having delay issues.
Usually PVA and PW reset happen when there are too many accounts connects to one proxy. I use 1 proxy per 3 accounts.
or it can be an age of account related issues, I use accounts from 2012, PVA'd with USA numbers.