Well David, it is kind of like an auto repair,
would you rather replace a tire after 60000 miles, even if it looks like it would last longer, in your own driveway, on a nice day, at your convenience, or rather have the tire fail 300 miles away from home, on a dark and rainy night on a muddy back road? and risk the extra damage to your car?
once folks give you an idea of life span for a heat tape, if you are near it, you may want to consider replacing the heat tape on a nice dry summer day..... because I can personally tell you, it sucks having to do it on a 17 degree day, with the wind blowing. the darn concrete is cold, even though you put a sleeping bag on top of it to lay on, and that is if the store have the heat tape in stock... which I got lucky.... nuff said, that bad memory from last winter too will fade, along with the thermostat dead battery turning off the furnace from this winter lol
interesting thing the contractor did for this last home he put the heat tape on, it was the long metal type, he put a loop of the tape up through the skirting, I can hold the loop in my fingers to see if it is warm, without removing the skirting, which has been nice to be able to check so quickly if the tape is functioning on very cold days.