Actually now that I think of it it would have been neat if the game had an actual indicator of 100% completion (like Bully, for example) that tracked all the side quests and stuff to let you know if you'd done everything possible. Granted for completionists it might have been a source of frustration and it might have taken away from some of the more "secret" aspects of the game but maybe for the remake it would be cool to have that as an option or something.
On-topic as I recall if you want to get all the materia you have to keep going back to do this mini-game at specific points in the story to get the final reward of a specific materia (don't remember which). Back in the day I actually enjoyed it as a mini-game but it was frustrating if you missed a specific point in the story to go back and do it again because you would miss out on those rewards.
I remember a really ridiculous 100% guide online that suggested cloning every item with the clone-item trick until you had 99 of everything. That would be beyond pointless and annoying.