The highest ITT/TIT/EGT is always seen as brief transient during start, during initial takeoff thrust setting, or during slam accelerations (go-arounds). On the General Electric CF-34-3B1 (the engine used on most Regional Jets and originally developed for the A-10), the max ITT is 900C, which is allowed for brief transients during starting, slam accelerations, or during takeoff (up to 2 minutes).
Outside of those conditions, you are limited to the Max Continuous Thrust temperature limitation (the normal climb thrust setting). On the CF-34, this is 874C.
On a fresh engine, temperatures seen will normally be well below these values when the fan RPM is at its limit (98.6% N1 for Max Continuous on the CF-34). This is called "ITT/TIT/EGT Margin" and is the main engine health condition indicator.
As the engine wears, temperatures creep closer to the limit values as efficiency declines, and eventually you start getting overtemps on start, or you can't achieve rated TO thrust or Max Cont thrust fan speeds without exceeding the temperature limits, and the engine is ready for overhaul.
But in any case, you will see the engine get pretty close to temperature redline during starting (less so with FADEC engines that manage the start fuel flow much more precisely, and will even auto-shutdown if there is an exceedance), and you may see it very close to that when setting TO thrust with a tired engine, but beyond that the temperature values are always lower for climb thrust, and lower still for cruise thrust, simply because you aren't putting as much fuel through.