Anyone Else Notice Hot Spots in Flexible Heaters?

I’ve been looking into flexible heaters recently, and something I find interesting is that reaching the target temperature doesn’t necessarily mean the heating is uniform.

From what I understand, a few things can affect where hot spots show up:

• Trace spacing
• Current density
• Sharp corners in the trace
• Uneven contact with the surface
• Insulation and thermal conductivity
• Power density

I’m still learning about the design side of this, so I’m curious how others look at it.

When you’re trying to get more uniform heating, what do you usually pay attention to first — the trace layout, power density, or the surface the heater is attached to?