Depends on how long you want the gun to last, and how reliable you want it to be.
Personally, I can't afford to buy a new shotgun because I let mine deteriorate, and I sure can't afford a stoppage on a HD gun, so I field strip and clean EVERY time I shoot it.
Pump guns are marvelously reliable, but all it takes is a grain of burned powder, a particle of plastic or a particle of metal case head to cause a stoppage.
I at least brush everything out with a toothbrush, but I clean the bore, the bolt, the magazine, and especially the chamber and locking lug on the barrel extension.