Heat tape hotspots: any way to dampen?

[jplehmann]

So if I have my shelves dialed in at max of 95 degrees on inside of tub directly on plastic (targetting 90 on top of newspaper

No, not on top. You always want the temp of the surface your snake can touch.
Don't worry about on top of the substrate.

I believe I should care about both of those temperatures. The direct plastic is for safety and not exceeding a temp, say 95 is top priority. But of second and still high priority is getting top of substrate to the ideal range for general health (e.g. 90). Not trying to argue, but why do you say I shouldn't care about that also?