
I have the same issue with completing games to do it. Sometimes it's a matter of "I can get a Platinum in this easily, so I will" like with the LEGO games.
I'm debating whether to 100% Yakuza 0 because of how close I am to doing so or stopping when I get to the mahjong achievements I really don't care about. I've already used tons of guides for the pocket racers, which is something I usually have an issue doing because I like to say I figured things out for myself ... but I care too little about modding those cars just right to do it over and over until I get exactly the right setup.
I think I need to go back to what I did in the old days: buy like maybe 10 games per system cycle and just milk what I want and fill in the gaps with rentals.
Happy gaming!