If only I had the luxury of a concrete floor! Lol!!
Yeah, I use plywood squares, but, I mean, I still work on hills / not flat surface so it's a bit of a pain to get something completely level. But, I try.When working on Cars without the luxury of a garage on a softer surface you need something to put the jack stands on. I have seen people use plywood squares, Railroad tie pieces, 2x4s, Paving stones, or Etc. to spread the weight over a larger area.