Recently I played FF4 for the first time.
I beat the entire game and did all the side quests besides the Adamant Armour one in about 2 weeks.
I didn't even need that armour anyways, I defeated Zeromus on my first try.
I tried stealing Dark Matter from him but grew impatient.
Didn't really need that either though.
I was surprised I beat it that fast, the other FFs I have played took me at least a month or so.
I still liked FF4, overall it was great!