Percent of complete titles is probably really low, maybe 15% I don't know but that could be way off. I don't really do the subscription thing other than earlier in the year I did for Doom, which I didn't complete. But whether I stick with something to the end or not depends on the game, I sort of feel a bit of an obligation to get back to Baldur's Gate II at some point cause it's this game with a totemic reputation, but I'm fine with taking really big breaks in the middle of games for some reason. But anything which gets really strong word of mouth puts me in a 'I have to know' mode, which is why I beat Blue Prince and Expedition 33 despite not finding them good, just pure stubbornness to know as much as possible cause of FOMO I suppose.
Otherwise there's things I'm happy to drop really quickly if I think I know well enough my opinion won't change, like Silent Hill 2 remake. I'm not sure why but there's certain things where I'm much more happy to declare them a waste of time bullshit, like Trails in the Sky. I think a game being old makes it easier for me to just move on from some reason, but when it's the flavour of the month I go well past the 'should have sacked it in' threshold, again cause of stubbornness.