Assumed temp. is used in most cases. Even in outside 36-40 Degrees Cent. we can still use 44 or 46 Degrees to cut the peak.
With the monitoring ability of Engine datas and maintenance from today the "standing time" of engines is increased significant the last 20 Years.
Whenever needed due to RWY, equipment failure or anything else: Full Thrust is used. Also once in 30 days was a proceedure I remember from a prevoius Employer.
Fly safe and land happy
NG