I cannot answer your question conclusively. I have tested the device for a long time with different operating systems and sometimes maltreated it a bit. Now it has been in normal office use for a few months, mainly with ASP applications, 5-6 x 6 - 9 hours per week.
I trust the device to withstand continuous use. It would be important to have good ventilation, sufficient distance from the base, not too close to other devices that generate waste heat. Room temperature should not be much more than 20 degrees C.

It is the mobile version of the Core i7 (not the desktop version).
I was able to determine that when overheating is imminent, the CPU immediately turns down the burst mode, which prevents overheating.
There are also various settings in the BIOS where you can decide whether you want higher performance with more noise or the opposite.
I use the NUC continuously as a server.