No backups done to the old 12-inch G4 PowerBook since March 8, 2017. Because that's when I could last find the specialised FW 400/800 adaptor & FW800/SATA interface cable & hard drive.
Yet, last night, when I needed that same adaptor & cable, I found them immediately. They were, oddly enough, where I'd left them.
SuperDuper! clone has been done, now working on the Time Machine backup.