Grew up in a house with a dishwasher where the sponge was just for getting hard bits off before going in. My parents have disgusting sponges, they will throw them in the dishwasher but don't wring them out between and use them for far too long.

I've spent the last 8 years in dorms/rentals/apartments without washers, so have spent a lot of time hand-washing. I may be a little OCD about it, but I have a very specific routine with sponges

-Cut all sponges in half, each sponge now lasts twice as long

-Always rinse and wring out fully, then put on a rack where it can dry out

-Replace sponges every 2-3 weeks, before they ever smell musty. This is why I cut them in half, and because I prefer the smaller sponge