Why have 3 external HDDs failed after a few hours of use?

I'd suspect, that those drives haven't failed at all - they were just running out of their specs and should be fine when plugged into a different computer.

Let me explain:

You use the USB ports of your Yoga for two purpouses:

• As a data connection, all fine with that
• As a power source for the drives, and that might be the problem.

Now the Yogas are notorious for providing less-than-promised current on their USB ports - this results in the disks being always close to starving for power, as writing to a 4TB drive typically comes quite close to the design limits of power draw.

You could use a (quality!) powered USB hub to overcome this - in such a pattern the juice for the drive would be provided by the hub's power supply, not the Yoga.