I'm gonna call BS. I've matured plants in all sizes of pots up to 15 gallon. Anything bigger is too heavy to handle(for me).
Six ounces of trimmed buds is the best I've done in 15 gallons.
Before you tell me I know nothing, look at my grow threads, linked below.
To the OP: do a search for a guy named Tom Hill. He has plenty of room and spaces his plants far apart, in 300 gallon smart pots. He's grown many 10 pound plants. Although I've never seen him mention it, I think his bigger plants have roots penetrating the ground under the smart pots.
A friend used to use very large "peat" pots ro get yields approaching a pound. I think they were 40 gallons.
Nukebiskit: I'd love to see pix of those girls. In my area, a plant capable of producing 3/4 lb in under 4 gallons would need to be watered three times a day, and anchored to keep the wind from knocking them over.
Not trying to be an ass, but I think some of these claims are stretching it, a bit.
. Its from last year.