Hard for me to define. I put 250 rounds because a typical club match is 100 - 150 rounds, and I'll clean every other time. I wipe down with silicone cloth when I put them away everytime, but cleaning is different.
In prep for a big match I'll clean, practice, clean, shoot twenty or so rounds and put away "dirty."
Small bore I clean after every match - 100 rounds or so. Hunting guns are cleaned after every day in the field. However, the "depth" of cleaning varies based on the climate and the amount of shooting. My Benelli got over oiled once and jammed from dust build up. I dumped a coffee thermos through it to flush it and keep it going. Even though it had only a few rounds that day, we had the owners manual out, and that thing was stripped as far as the book would tell plus a little.
Muzzle loader gets cleaned and oiled everytime it is used and even in between when it hasn't been shot. But, even with the modern powders it still has a nasty barrel.