So just as an experiment, I have three temp probes on the warm side right now:

1) Affixed directly to UTH, 85.6
2) Under substrate against glass, 84.3
3) Top of substrate (substrate ~1 1/2" thick to allow for burrowing), 76.4

Nearly a 10 degree differential between hot spot on top of UTH and top of substrate. So I'm still back at my original question: when a care guide says warm side 80-85, am I setting the UTH to 80-85 or am I setting the UTH a full 10 degrees warmer?

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Or am I jacking up room temp/providing overhead heat source?