Most keyboards today are merely computers. If we take the computer approach, most computers today that run in a Data Center are powered on 24/7/365. We perform yearly power down tests to ensure none of the computers fail on the power up sequence, test the quality of the power filters, and replace battery backups.

I would recommend a good power conditioner (the ones that have a backup battery in them) to protect your electrical circuit from voltage fluctuations which can kill electronics. JMTC

Al