I include an ice scan whenever I'm flying near icing conditions. Even
if the OAT says +2C you may really be in icing conditions due to errors
in measuring temp. For me, in my Mooney the first place ice usually
appears is on the very bottom of the OAT window gauge (you really have
to crank your neck to see the bottom of the end).
I'm firmly in the camp that there is no way, no how any IFR pilot who
really flys IFR on a regular bases can go through his entire career
without hitting ice where its not suppose to be. The skill is in
keeping yourself in a position to get out of it.
-Robert, CFI