But wouldn't this only be necessary if you found the same delay with a standard timing light? Sounds like this timing loss would be something in the control unit, not in the distributor itself, but can be made up for in the distributor. Do different control units have different accuracies?
I remember the old days using an oscilloscope in a raster pattern and looking for an "S" pattern to determine timing chain stretch. Something else that is hard to see with just a timing light.