"...This way, they can clog a bit with no performance loss."
I think, WW and others, that I remember being told that air filters (maybe oil, too) are designed to be better at doing their jobs when they're about 20% clogged with crud. They gain filtering ability as the large passages become slightly clogged, so build them a bit on the "loose" side and accept the fact that they'll catch some stuff. Within reason, of course, but a little dirt/salt in there is a good thing.