How long can the RYOBI Belt Sander run continuously?

Do not use belt sanders continuously 

You cannot use a RYOBI electric/corded belt sander continuously. 
Sanders used for long periods need regular breaks to allow the motor to cool. 

Prevent motor overheating 

If the motor overheats repeatedly, it could eventually burn out. 
Example: After 30 minutes of continuous use, allow a 5–10-minute rest before resuming.