I must admit I usually stick the thing on with the power checks and turn it off on the afterlanding or where ever its mentioned in the checklist. Doesn't matter if i am VFR or IFR summer or winter.
Asked the engineers if it is going to cost anything. Reply was no its a bloody great thick wired heater only time they had changed one was if some plonker had used the pitot tube as a hand hold.
I am sure some people will say its a high current device and your putting more load on the Alternators. But who cares, if it stops the failure of a primary instrument once in your flying career its been worth the small expense.
MJ