I've always said that I'd rather have too many than not enough.
However, if you feel like you need 8 or 10 mags, holding 15 rounds or so, you need to change two things in your life...
1. Stay away from places you shouldn't be.
2. Get more training and more practice.
If you can't get yourself out of a situation with 15-30 rounds, what makes you think another 20-30 is gonna help?
I fired exactly one round in the line of duty and that’s all that was needed. I still had five rounds left. As for magazines I simply view my excess as money in the bank....