TOF- we used to shoot at almost sea level right on the coast with high humidity and rain being an almost constant bother without fouling issues. The other extreme is up here when the humidity is in the 20% arena, still no fouling issues, so we've run the gammut. It even gets to the 100% arena here as well, where the pan is full of water, just from it being absorbed from the air and needs being wiped before re-priming.
We shoot the same, all of us, without having to wipe at any time. You are correct in mentioning loads, patch thickness and type of lube as having a direct effect on fouling. I've found the people having fouling problems usually use a poor lube, not enough lube, too thin a patch or too small a ball. All are interconnected in having a clean shooting gun. Clean shooting is a mis-nomer here, as the fouling from the previous shot is there, just that there is no buildup between shots. You have hinted ort mentioned this atteched to wetter lubes. On the other ahnd, in warmer weather, I've found the heavy lubes, greases like bore butter and lube 1000 to shoot just fine all day without having to wipe. Time between loading gives notable differences in loading with LHV lube, less so with spit. I havn't tested the others in this regard as I don't have any need for them. LHV does just fine if I want to go hunting and spit handles range duties with few or no challengers.
My wife used to shoot a .36 Senica back in the 70's without having to wipe the bore, whether she used the little 128gr. slug or patched round ball. Rendezvous always saw her using round balls, of course, a .350" with .020" denim patch, spit lubed. It was an easy load for her although she wasn't particularly robust at 110 pounds, back then. Today, she, still slightly built, she shoots a .45 barrel on the same stock and hardware, with same patch and a .440 ball with LHV lube - good accuracy, no fouling problems, even in the heat and dryness of 35% humidity.