I usually don't do tech comments or reserve them for specific people, but once in a while I'm not in a super chitty mood.

Idle speed, theoretically on the design table, isn’t based on how smooth the engine idles at however low of a speed. Idle speed is determined by the minimum standing inertia the engine needs for the best performance.

For instance, I can drop my idle down to about 350-375 with smooth operation. (Actually it sounds pretty badass at that speed, like a predator lurking the bushes trying not to draw attention by breathing.) The problem is that it won’t ‘wake up’ as quick because the lack of standing inertia.

You also mention checking/adjusting timing, something that affects engine idle. This opens doors where it has been obvious in the past that I am wasting my time making comments. With that, keep in mind that timing adjustments affect idle speed.