Not as much as everyone makes it off to be is what we are sayin. It doesnt mean i use a one gallon pot from start to finish, depending on the plant size thats what you should go by. But use common sense, not all the bs about how you are going to "increase your yield by double" Like i said I use a beer cup after they get out of the clone chamber and are well rooted. Then by knowing when those are well rooted i put them in a one gallon pot. I let mine veg to about 16-18" on the dot and put them in flower. After the transition period they are ready for 3 gallon and I let it ride out. I believe having a 5 or 7 gallon will not make a night-day difference.