[Marcel Risberg]

Simple answer: No, it would not be bad for the drive.

It's a bit like asking if it's bad to drive a car for hours. No it is not - but of course I'm assuming now that the car is proberly built and has a working cooling system.

A bit more detailed: So, if your drive is configured and dimensioned correctly, including the external housing, you can have it work for hours without concern. If you are concerned, maybe you looked for a cheap backup drive rather than a high quality build, then you could monitor the heat of the drive by touching it after 20 minutes of use. If it's hot to the touch aim a fan to it to cool it down and make sure it won't degrade faster than normal. If it's not, we'll let it do its thing.