roots

I have a screwed up grow so gonna start over with seeds, I posted a question a while back about planting in big pot from the start and the reply was seems it'd be ok .....well I was talking to another grower who said I needed to go from party cups to small pots and step up in stages. His explanation was that the roots will spread out till it reaches the side of the pot and then grow down only utilizing the soil on the sides of the pots wasting all the soil in the middle. Anyone heard of this ? I really don't want to mess this up so I want to be clear as possible. BTW here is why I'm starting over.....

Think of how it grows naturally outdoors.
The bigger the container, the better. (depending on what YOU want though)
Bigger container=bigger plant
My um, friend, uses 1 gal containers to keep their plants roughly 2 feet or less. I hope this helps.

I start in party cups wait for a good root mass. next pot is about 4x the size of the cup and then do the same thing each time the roots fill the pot. I max out at a 2.5 gal pots then plant outside. If your not going outside pots can go to 5-30 gal. the bigger the plant bigger the pot. The key is good root mass before transplanting to a bigger pot.