I actually think the wall clock time that is used here is a more useful metric here. Using as few keystrokes is not necessarily most "efficient" in time if you have to think longer about which ones to press.

I worry about this, I feel faster using a simple set and mashing, but how do I know I've not just settled into a local minimum.

I think is why I like the jumping plugins

You are looking for this: https://github.com/igrigorik/vimgolf

Hmmm, thats interesting. Right now it just shows every character press, regardless of what it was to achieve.

You'd be interested in something a bit more organized, so you can see how they got specifically from one target to the next. I do have a ton on the roadmap right now, but that has been added as well!

It shows what the people on the leaderboard used, seems close enough.

You can load the leaderboard and see what keys they used. E.g. number 2 finished in 1.002s and used these keys:

ArrowRight, ArrowRight, ArrowDown, ArrowRight, ArrowUp, ArrowRight, ArrowRight, ArrowRight, ArrowDown, ArrowLeft, ArrowLeft, Shift, ArrowUp, ArrowUp, Shift, ArrowRight, ArrowRight, ArrowRight, ArrowDown, ArrowDown, ArrowLeft, ArrowUp, ArrowRight, Shift, :, 4, Enter, ArrowDown, ArrowDown, ArrowDown, ArrowLeft, ArrowUp, ArrowLeft, ArrowDown, ArrowLeft, ArrowDown, ArrowDown, ArrowDown, ArrowDown, ArrowDown, ArrowDown, ArrowDown, ArrowDown, ArrowDown, ArrowDown, ArrowDown, ArrowDown, ArrowUp, ArrowLeft, ArrowDown, ArrowDown, ArrowLeft, ArrowUp, ArrowUp, ArrowUp, ArrowUp, ArrowUp, ArrowUp, ArrowUp, ArrowUp, ArrowUp, ArrowUp, ArrowUp, ArrowLeft, Escape, Shift, :, 1, 1, Enter, Shift, :, 1, 0, 0, 0, Enter, ArrowDown, ArrowDown, ArrowDown, ArrowRight, ArrowLeft, ArrowLeft, ArrowLeft, ArrowUp, ArrowUp, ArrowUp, ArrowUp, ArrowUp, ArrowUp, ArrowDown, ArrowLeft, Shift, :, 5, Enter, ArrowDown, ArrowDown, ArrowDown, ArrowDown, ArrowDown, ArrowDown, ArrowDown, ArrowDown, ArrowDown, ArrowDown, ArrowDown, ArrowDown, ArrowRight, ArrowRight, ArrowRight, ArrowUp, ArrowRight, ArrowRight, ArrowRight, ArrowRight, ArrowLeft, Shift, ArrowUp, ArrowUp, ArrowUp, ArrowUp, ArrowUp, ArrowLeft, ArrowDown, ArrowDown, ArrowDown, ArrowDown, ArrowDown, ArrowDown, ArrowLeft

...