I honestly do monitor the TAT or OAT or whatever you have...I even keep a bit of a log...(certainly this is in level cruise). Its not that hard, just put it into your scan.
I must admit I learned it from a film, rarely seen, called, "The Pilot"...with Clift Robertson...its an interesting film...look closely when they remove the DC8's trim cover and giggle.
anyway, it is true that a sudden change in temp can warn of CAT. And I've found it in other aeronautical publications.