Pendulum clocks when running properly will run right on the money. Millimeter changes in pendulum weight height are what you want to go for and then let the thing stabilize a few days.
This is exactly what I am learning. Small adjustments and don't be in a hurry to do the next. It has been a long time since I have been in a shop full of clocks ticking away but in hindsight I imagine they were getting them in tune.