I have always ben sceptical of the theory that one gets the best growth
from potted plants by following the advice of using only a slightly larger
pot than before when potting-on. This doesn't emulate nature, which usually
seems to do things quite efficiently, when left alone, out in the wild-and-
woolly wilds...

If you follow the advice, it seems to me that you end up with an
unnaturally dense root structure, with an unnaturally small amount of soil
between each root from which to extract nourishment.

So is the "next-size-up" advice good advice, and if so, why?

Thanks,

Al