Shutter Speed Accuracy

As many LTM and M camera bodies have seen decades of use, has anyone seen a study of shutter speed accuracy degradation over camera body lifetimes? If so, will a proper CLA'd LTM body regain and then retain shutter speed accuracy as well as an M body? Or the opposite?

Yes, a CLA done properly will have the shutter speeds adjusted to within tolerance. I don't know the Leica factory tolerances, but most 1950-70 bodies considered about 6-16% or 1/3 stop to be within tolerance. Whenever I acquire an additional old body I run it thru my shutter tester, and generally the shutter speeds are as stated above. What is equally important is that when repetitively cycled, the actual speeds for any given stated speed on the speed dial are consistently within tolerance as usually each time a shutter is fired, its speed will vary slightly from its previous fired speed.

If the speeds are off, will they tend to be slow in most cases?

In my experience, yes, if measured speeds consistently show up outside of tolerance, they have tended to be on the slow side. Generally I don't worry about that as long as I know approximately where they consistently fall, I can make appropriate exposure corrections.

As many LTM and M camera bodies have seen decades of use, has anyone seen a study of shutter speed accuracy degradation over camera body lifetimes? If so, will a proper CLA'd LTM body regain and then retain shutter speed accuracy as well as an M body? Or the opposite?

If done properly, a CLA will restore a LTM or Leica M to its factory specs. It's particularly easy to tell if a Leica M camera is out of adjustment simply by listening to, if you know what to listen for, the slow speeds.