DDG...
The thermal qualities of the aluminum used is not so sensitive that a degree or two make a difference...10-15 degrees yes, otherwise, forget it.
A few younger guys want to make a federal case out of this, oh gosh...a degree or two, OFF, then as the TAT cools, ON again.
You exercise the switch/valve too much, next time (when you really
need it), it fails...closed.
Then, bad news.
Much better to keep your powder dry, for when it really counts.
Tto make the job
harder than it needs to be is, in my opinion, to distract the crew from the job that really matters...flying the aeroplane.
Yes, limitations need to be regarded, but to split hairs never got the job done properly...and indeed may lead to distractions, which
cause incidents/accidents.
And these, are
absolutely to be avoided, if possible!
Edited to add..
Have personally noticed ice on the inlet cowl at temps at +12C TAT in TriStar aircraft...better leave it ON to be
sure.
411A, I trust you read the comments on the other (now closed) thread. I have edited out the more objectionable parts of this post and you know what? All the information is still there. The difference is it is now presented in a professional, informative, polite way. I hope I shall not have to remind you again. You are sailing a little too close to the wind.