RAV4 2007 Brake Pads

If you went from 70% to 20%, then you used roughly 50%. I'm not sure there is anything to be alarmed with here.

I was once told by the dealer that my daughter's Tacoma needed front brakes. I went and bought new pads because I can install them myself. I discovered that the worn pads has more than half of the material of the new pads, so I put everything back together and put the pads on the shelf for future need.

You can do the same. Or you can take a tire off and look to see how much is left, then buy new pads or not depending on what you find. It doesn't really matter how much you have used, it only matters how much is left.