I trace the profile onto a piece of lumber or paper so I can refer back to it and see where the set is occurring and just how much. Some of those highly characteres ones are hard to tell they’re taking set until it’s too much if you don’t have a reference to where it started. I do a lot of the tillering with my hands on the wood to feel areas flexing while I’m working it on the tiller tree. If you place you hand different areas of the limb while flexing it you can feel if it’s working or not. I’ll watch it work for quite a few more pulls than a clean profile and if I question if it’s working I’ll feel the wood to get a better idea of what it’s doing.
Kyle