True. Another trick I found that worked was to put a sheet of that foam insulation with reflective coating on it. Like the ones you use for attic walls or house walls. It helps on the thinner pvc cages. And yeah, tall cages can be a pain. A long cage you can use one that is about 1/2 the length of the cage, should work. I'm using a Pro Products 65 watt RHP in my 4x2x14in Proline HDPE cage and it keeps it plenty warm but I also keep my house fairly warm at 75F so that helps too.