Ten and two. Acceleration and crisp stops between two points. Pause and allow turnover to happen. Feel the rod load and watch it all happen with the fly line in the air. Once you have that timing, your baseline is set, and you can take that same stroke to any rod angle, punching the fly around and laying things out just how you want them with a few adjustments.
Good mending is setup by good casting. Put the two together, and you can feed slack to a dry fly for perfect drag free drifts.