I remember that expression from someone who advised companies on strategy. Focus on what you are good at and make minor changes on the peripheries.
Since I started racing IOM's, I have used the same setup numbers, whether it be for an Alternative or a Britpop and they are all the standard numbers published for the designs. Of course there are things I have learned about the minutiae of tuning. Half a turn on the kicker here, a nats of adjustment on the mast ram, a mm or two on the jib luff tension as the wind builds. All these things are trialed through experience.
I put a new A rig mast together this week with some nice prebend put in by David Potter and the final rig and older BG sails look fantastic. All the measurements are the same and my only real challenge was to get the shrouds to be identical lengths.
So what about the stick to your knitting bit. I think that is working to get off the start line with a gap to leeward and sailing fast to keep the lane. If you can get the first tack in ahead of the field, the battle is half over. Oh and the other bit for me, is to avoid the awful results which I seem to do with monotonous regularity. Bearing in mind these boats sail themselves we have little to do but organise our way round the important parts of the race course.