Can I constantly run motors for an extended periods of time?
Pittman motors don't appear to be hobby or toy motors. They appear to be designed for continuous use. Lower than max voltage would be reduced speed. They may have some minimum speed for continuous operation. You should look carefully at the specifications for the specific motor and gear that you intend to use. Check the gear efficiency. Even if the driven load is very small, you need to consider that these motors are very small and a significant percentage of the motor power may be required to overcome friction in the gear.