I try to keep it as simple as simple as possible.
For revolvers, I bring paper cartridges, a loaded Polish capper, and a few tools for emergencies. I normally have around 100 cartridges on hand, so usually do not bring loose ball and powder to the range anymore. I also no longer bring cleaning supplies as I find them unnecessary. Everything necessary lives in a very fine oak box that I had made several years ago.
I have everything I need for flint rifles in leather shooting bags, so when I take a flinter to the range I just grab its bag and powder horns (one for pan powder and the other for the main charge) and know that I will have what I need. These bags contain the usual stuff - various jags and brushes, patches, flints, round ball, and small tools for replacing flints and such. Still no need for "serious" cleaning supplies. A bore brush and lubed patches will get me through a day afield.
My long range rifle still requires everything plus the kitchen sink. Putting all of the rods, tubes, vials, bullets, and on and on in one box would make it too heavy to lift, so gathering and transporting all of that crap is a major undertaking. With the other guns I can just grab and go, but this one is such a project that I have to plan ahead and reserve the entire day for it.