Does raising speaker cables off the floor really make a big difference?

I like tweaks and have a bunch of them. This one has never revealed itself as sounding better.  I run my cables under my floor in my conditioned crawl space and my system sounds the same as when I had those funny looking ceramic risers all over the floor holding my cables.  No change. 

I suppose it depends on the room, flooring material, cable length, cable covering,  cable weight and perhaps many more variables.  I suppose room humidity also plays a role.  Easy for us to have differing experiences with this lifting tweak.