I guess it's worth mentioning in the post here that I did pick up a 10-string railboard - so let the fun begin!
Maybe because I'm approaching this as an adult and it's different enough from guitar, orchestral strings, piano, etc., which I approached as a kid and have since left to "autopilot"... but I find myself needing to think a lot more about intervals when plunking around than I have on other instruments. Maybe because I've tended to ignore them so much in the past and just rely on rote visual patterns.
Also I'm finding my left hand to have surprisingly little reach/dexterity folded in at close angles vs. when held 2-3' away at the end of an outstretched arm, but I guess that'll just take some getting used to.
But after only a couple days of actual "practice" it seems to be starting to make sense, so that's good!
Wish me luck!