Actually using that thickness of foam can cause too much reverse pressure on some tank bottoms and actually could cause issues.
Because each are built different, you really should know and do what that particular tank manufacturer recommends.
It depends, as already stated, on how the bottom of a particular tank is configured. Certainly, a tank with a floated bottom (rimless; bottom up inside the sides by 1/4" or so, and rimmed tanks) will/can easily destroy the bottom if using foam. Semi-floated or non-floated bottoms, because the weight is not supported around the edges, rather spread across the bottom of the tank, even 1" foam, should not really cause a problem. However, most manufacturers are going to say "somewhat thinner" say in the 1/2" range, some will say just a "mat."
That said, since this is a significant topic, if the documentation for the tank does not included information on this topic, (which I find surprising, though it happens) it warrants a call to the manufacturer.
The rimless cubes (Marineland) are something of an enigma. I don't know how the bottom is configured, I see a split bottom seam in the pics of them, and I don't see a bottom frame. In my book, a rimless should not be on an open top stand, unless it has a full floated bottom, making it no different than a rimmed tank (at the bottom,) but then I don't work for, or speak for Marinland.