Had a 254k run today that ended with a tumble down the elevator on 8-4.
Some reflections so far;
I'm doing relatively well on barrels (from level 5 where the barrels are easy to steer and the wild barrels are more predictable) and springs, but I can struggle a lot on the pie factory if I don't get a clean shot at the ladder. The rivets are maybe my worst level, where I am not good enough to improvise a pattern when going for the star is not the appropriate course of action. I should try to improve these by doing more savestate training.
I don't go for any extra points anymore as I don't feel it is a good use of my time right now - I would rather let the score always more or less reflect how far I made it in a run.
You should be able to clear any given board post level 4 at least 19/20 times on average to reach the kill screen fairly reliably it seems. That could take a while...