My least favorite was in FFIX where, not only were there a TON of missables, one of the best weapons required you to get near the end of the game in under 12 hours. While its technically possible to 100% everything in that time, you absolutely need to be following a guide to do so, so your choices are A) end up at the end with obviously incomplete sets of items/cards or B) turn one of the best games of all time into a checklist. Fucking lame.