Is 21 pairs of underwear overkill?

I've had friends tell me 7-10 pairs of underwear are enough.

I've always kept 21 pairs, so 3 a day, in case I need to swap them after exercising or for whatever reason.

How many pairs of underwear do you have at any one time?

I have about 80 pairs of socks.

I typically do an underwear/socks wash every 7-14 days depending on how much of them I use.