Had to look it up, but I paid a bit under $5 in total last year. Mostly towards the beginning of the year when I didn't have my bills set up properly (i.e. the timing didn't match my direct deposits at first, had to make some calls to change that) and from some large ticket purchases that a single paycheck couldn't fully cover (with sufficient planning those could have been avoided if I sold some stocks beforehand). I haven't needed to make use of margin at all for well over 6 months now.

Schwab's margin rates are on the high side, starting from 7% and up, but even then if you're borrowing for 2 days at a time the cost ends up being negligible (about ~$1 for every ~$3000 borrowed). At the very least, it's much better than most overdraft fees/lines of credit. Though if Interactive Brokers were to offer a bank account, I'd be very tempted to switch with their amazing margin rates.