I think I have the same "once & done" on my Job 2 '08 MMH.

Wed 1/7 Update: I put my seat heaters on this morning and after 20 minutes they were still "heating" me. I think they might have cycled on/off. I was unable to keep focused on them due to snow/sleet storm I was driving in (was focused on driving). I ended up shuttin it off as I felt it was too warm with the "cabin" also heated up. Sorry for the inaccurate speculation above.

 

I noticed one of the respondents said their heated seats got really hot, really quickly, then cooled down. Ours get so hot we turned them off almost immediately and we've been too chicken to keep them on for fear of frying our thighs. Is there a fix for this or are we simply stuck with it?

 

You don't say what model or year you have.

The seats should turn off automatically - they should not continue to heat. If the heat doesn't turn off after a few minutes the you need to take it in for service.

I have not seen any definitive numbers on how long it takes to cycle. My wife likes the heaters; I myself never leave them on for more than a couple of minutes - I don't like the heat. But she has never complained of roasted butt!