Useing a pot that is much larger than your rootball alows the medium to retain more water but at the price of exluding more oxygen.
Stepping and matching your pot size as your plants grow will be more beneficial than plonking them in a big pot from the start.
Beware of the 30l pot, I grew some 8 foot trees in those before...
here is one that was topped to make 4 main colas, so it could have been even taller if just left to its own devices.