Repeatedly dis-assembly and re-assembly wears the weapon?
Some of the older Army publications indicate repeatedly dis-assembly and re-assembly cause unnecessary wear and tear on the weapon. This is probably true to some degree and true, depending on the exact mechanical nature of the thing that is taken apart and put back together again.
The gentleman that says he does his complete take down only occasionally may have the right thing going on here. But you have to find a way to keep the weapon preserved in-between times with either oiling or wiping or both.
I have immersed locks and that sort of thing in oil and dishwater and oil again without taking them apart, and it has worked well enough for light soiling.
Many of the black powder guns are soft steel, and screw and bolt heads will show signs of wear, as will threads if they are disturbed too often, or even disturbed with a tool that doesnt quite fit; such as a screw driver of the wrong size, or using pliers when you should be using something else, etc, etc.
I would imagine good tools, and only occasional deep dis-assembly would be the best idea, with adequate oils at all times.
The Hawken is really a great system, because it comes apart easy, and even removing the lock is the easiest thing in the world. Few fasteners and few contact points. Cleaning my Hawken is a piece of cake compared to some of my other guns.