The Verus controller adjustment is in 0.16% steps. This means that the worst case speed error will be 0.08%. On average the error will end up being about 0.04%. Doug had a very early controller that used adjustment steps that were much larger. All of the controllers have been upgraded to use the finer adjustment steps.
A continuously variable adjustment scheme would be less accurate because analog circuits drift. You can get the speed spot on but does not stay that way. With the Verus controller you may end up with a small speed error, but it will stay exactly the same and does not need to be re-adjusted. It would be very difficult to get an analog circuit to remain within 0.04% over a long period of time.
A continuously variable adjustment scheme would be less accurate because analog circuits drift. You can get the speed spot on but does not stay that way. With the Verus controller you may end up with a small speed error, but it will stay exactly the same and does not need to be re-adjusted. It would be very difficult to get an analog circuit to remain within 0.04% over a long period of time.