Every Friday, me and some friends go out to eat at some Hong Kong cafe, and have to split the bill. So I typically withdraw $20 every Friday afternoon, and carry the remaining cash for the next week. That usually runs out by Tuesday or Wednesday, though.
So on average, I carry $10-$15 in 5s and 1s throughout the weekend and the first half of the week, and I'm using my debit card for the rest of the week.