Necesity of multiple layered platform
How necessary is it to build a platform with multiple levels of plywood?
I've seen a ton of designs with two sheets lengthwise, then two sheets on top of them, then the top layer is rubber and some decent grade wood.
I know some places just drop a single sheet of ply in between mats, usually right on top of the cement floor. Does that not cut it?
Also, I've seen some (like the ones at California Strength) that look like a ton of 2x6's stacked up side by side.
So again, what's the benefit of the extra cost of a couple more layers of ply?