I was mainly referring to having the drawbolt fully tightened, and not necessarily tightened to any particular tension. I do think it's important to have a well-designed wood-to-metal junction, in order to have a consistent tension on the rifle, but (so far at least) I have no specific info or opinion on the optimum amount of tension.

Specific examples of poor drawbolt wood-to-metal junctions include the 1878 Sharps Borchardt and many examples of converted Win walls.

The Borchardt needs internal grooves for hidden forward extensions of the wrist wood, to keep the sides from spreading outward over time. You can see the resultant damage when you examine many if not most old Borchardt muskets, almost all of them have cracked and otherwise damaged buttstock front ends where the wood meets the metal. Frank de Haas makes reference to this problem.

The problem is just the opposite with many walls that have been converted to drawbolt, in many cases the front ends of the wrist wood will be forced inward instead of outward. Many of the older conversions used a block attached permanently between the tangs, necessitating that the hidden wood between the tangs be cut completely away so that the buttstock could be slid forward around the block in order to seat. Well, when the drawbolt is tightened in such an arrangement, the front ends of the wrist wood are compressed inward by the angled rear scalloped areas at the rear of the receiver, and now there is no longer any wood between the sides to provide support. Without such support, the sides will spring inward somewhat upon the recoil of firing and therefore don't provide the rigidity desired. A well-designed wall drawbolt will have almost all the wood left remaining between the tangs, for side support at the front, with some sort of arrangement such as a removeable block or a tang screw sleeve. This problem is mentioned in much of the old literature such as Landis' fine books.
All for now, good luck, Joe