bigger pots

I have been reading that you dont need to transplant untill the plant is root bound, and in doing so the plant will continue growth, but is their a size that is too big for a area?? right know i have two plants that are in 5 gallon buckets and are about 4-5 ft tall, i was wanting to increase...

:tokin:this is gonna be my first grow. i bought three 600 watt hps with digital ballasts and got some clones of the sour deisel. i got a couple t5s for veg, cloner ect... i for sure got the space the only thing im wondering is should i put nine per light with bigger pots or twelve with smaller...