Like said above, "need it"? Probably not. Depending on your setup, a half canister full of a few dollars worth of plastic pot scrubbers or pennies worth of pea gravel will provide the same service as expensive store bought bio medias.
To me, the biggest advantage to having 'more' than you need is to have the ability to setup a new tank instantly.
Another thought is, is there a point of having an amount of bio media so large, that your mechanical media can't keep it clean of solid debris? On an oscar board I frequent, there's folks there that remove and replace a portion of their bio media, every time they service their canister filters. The claim is the pores in the bio media become clogged with dead bacteria and debris over time and thus reduce it's surface area for BB to colonize.
They basically boil the old stuff and put it back into rotation. I do not have the ambition to join that movement at the moment.
