Every month or so I review my direct ancestors and check the folk furthest back on each line. Occasionally I come across a fresh nugget which has appeared online, and another half a day is needed to follow it up.
So not invested in one ancestor these days, but I did spend a LOT of time searching for my direct paternal gggg gf's origin. Found a lot about my ggg gf on the way, including nine different spellings of his surname - none of which matches mine!