It's the maximum amount of time by doing everything that's possible to be done in those games, at the first try. I'm a perfectionist when it comes to games that I like, I don't go to the very end if I don't have a 100% of the game xD
FF X is one of those examples, I didn't stop until I had 255 stats, 64000 max HP, 1200 max MP, all Dark aeons, Penance and Nemesis defeated, more than 120 blitzball matches won, will all my players at level 99, all the shots learned, all overdrives learned too, all the Celestial weapons powered up, so that accounted for 250+ hours of gaming, since the main history, until after the Jecht Final Aeon battle was only 60 hours or so.
Edit - Oblivion could be easily done with in less than 40 hours actually, but I didn't get to the main quest until I had all dungeons, caves and ruins explored, and all other side-quests done, all guild quests done, and even then, during the main quest, I went and closed the most number of Oblivion gates as possible
Current PC Build
CPU - i7 8700K 3.7 GHz (4.7 GHz turbo) 6 cores OC'd to 5.2 GHz with Watercooling (Hydro Series H110i) | MB - Gigabyte Z370 HD3P ATX | Gigabyte GTX 1080ti Gaming OC BLACK 11G (1657 MHz Boost Core / 11010 MHz Memory) | RAM - Corsair DIMM 32GB DDR4, 2400 MHz | PSU - Corsair CX650M (80+ Bronze) 650W | Audio - Asus Essence STX II 7.1 | Monitor - Samsung U28E590D 4K UHD, Freesync, 1 ms, 60 Hz, 28"