I've been trying to figure out on my own testing and i'm not sure really so looking for input in the subject.
Say i just crafted a 4 star sword, would leveling it's heat go faster if i wear all 2-star items that are level-10-complete, so all of the heat i gather is funneled into that one item, or will it level at the same rate as if i wear 2 other 4-star items and go through and gather heat and level all at the same time?
I guess what i'm asking is if you have multiple items on that need heat, does it distribute the heat you gather between all items? or do all items get an equal amount and level at the same speed?
Heat that would go to level 10 equipment would go to equipment that isn't already level 10. Thus, the fastest way to level up a piece of equipment is for it to be the only non-level 10 thing you have equipped.
And yes, it distributes between all items. Higher star-rated items level up slower than lower ones.