It sure is. Running a motor for such a long time, 10-12 hours likely exceeds the duty cycle of the motor. Many small motors self destruct by running for that long time. The cooling is not good enough, or is absent.
I've got a micro mill, an MF70. Measuring the spindle motor temperature, motor running without load, the temperature just keeps raising. Of course I toasted the first motor letting it work.
To run a motor like You do, 10 - 12 hours per day You really need to find a sturdy motor made for continuous running.