
I'm told it takes a very, very long time to master every craft. Disiciples of the Hand are the hardest class to level, and that only gets magnitudes worse at the highest levels.
There's also the issue of inventory space for all the crafting ingredients and equipment you'll need. You get 200 slots on your character and 150 each on two retainers. 500 slots sounds like a lot, but when you factor all the other things you'll want to hold on to like food, potions and other sundries, +1 ingredients and the many flavours of materia, it's going to be very tight at best.
There's also the issue of inventory space for all the crafting ingredients and equipment you'll need. You get 200 slots on your character and 150 each on two retainers. 500 slots sounds like a lot, but when you factor all the other things you'll want to hold on to like food, potions and other sundries, +1 ingredients and the many flavours of materia, it's going to be very tight at best.