I hope it's got my preference for the proper amount of side quests. I'm playing Final Fantasy VII: Crisis Core right now. There are 300 missions. I've completed the first third and they take an average of 5 minutes to beat. As I beat the rest, the average time for them will increase. The main quest itself may take 13 hours. In this sense, this game reminds me of The Elder Scrolls IV: Oblivion, a great game, but it's basically all a sidequest. Since the main quest is under 20 hours I think and finishing the entire sidequest stuff takes over 300 hours.
I finished Final Fantasy XII with maybe a 90% completion rate, and I think I skipped only about 25 hours of sidequests. I had to finish the side quests slightly prematurely since Final Fantasy XII: Revenant Wings was right about to come out. I'll give you my information for a Final Fantasy XII 100% completion rate attempt. If I continued on to that, I'll give you the lengths I think it would be. Keep in mind that this includes roughly 125 hours of using the Negalmuur auto-leveling method. Also keep in mind that some people will go through the game faster. Also, maybe I underestimated the length of some other sidequests like the Bestiary completion.
300 hours for 100% completion rate. 75-100 hours for the main quest. 75-100 hours for the sidequests. 125 hours for the Negalmuur auto levelling method. So it appears that 50% of Final Fantasy XII was sidequests. I think I enjoyed this amount of sidequests for Final Fantasy XII. This is because it's a main Final Fantasy numbered title and I'm okay with it having a ton of sidequests. For a less critical but still great Final Fantasy game like for example Final Fantasy Crystal Chronicles: The Crystal Bearers, I wouldn't want it to have so many sidequests, if I played it. For Final Fantasy VII: Crisis Core, the main quest may be 15 hours long and the sidequests(95% of this is missions) are about 55 hours long. For Final Fantasy VII: Crisis Core, I think they went way way way overboard on the sidequests. Even if it had a longer main quest that was 55 hours long, 55 hours would still be too many sidequests for my preference I think, since it's not as important to me as some other game. Anyways, it's up to me to decide whether or not to do the sidequests. I'll do them since I have time for them, not in a hurry to beat the game right now. Hopefully some posters read this long post. I am hoping that Final Fantasy XIII has the proper amount of sidequests. Since it's a main numbered title, I wouldn't mind it having 75-100 hours of sidequests like Final Fantasy XII, as long as the story is atleast 75-100 hours long by itself.
Recently beaten: Alundra 1, Final Fantasy VII: Crisis Core
Currently playing: Final Fantasy Tactics A2: Grimoire of the Rift, Final Fantasy I
Will play next: The Elder Scrolls IV: Oblivion, Mass Effect, Fallout 3(???)
*Last Update 7-25-2008