If you're really trying to do everything, it's more time consuming than you can imagine. For example, try getting 99 Iron Bangles. Since the window of opportunity is so limited, the only fights available to you give 24, 24, and 30 gil. This takes hours.
Then there are the situations that test your commitment. For example, the A, B, and C are Key Items, exchanged in the Shinra Building for a Star Pendant, a Four Slots, and an All Materia. Are you really going to skip that All to keep a Coupon meant solely for that purpose? If you're going for true item completion, you will.
Which brings me back to my earlier point. No one is going to satisfy every requirement someone can think up. Do whatever you feel defines a master game, and remember to enjoy FFVII while you play.