I use Hydro V's and squeeze mine out once a week after doing 100% water changes daily. A lot of stuff comes out despite the big water changes and over filtration (2 sets of double stacked Hydro V's in a 75 gal tank). I'd think eventually they'll get clogged up without squeezing. I've since started switching over to the large pore Hydro's, which they list for ponds. Stuff will come out them too every week, but much less.
I'm sure the sponges can do with less squeezing, but when you're OCD about discus...
Willie