> Scan the backs

I guess this is assuming some scanning rig (camera scanning?) where it only takes a few seconds per photo. With a flatbed scanner, scanning the backs is almost certainly going to take longer than just typing dates in manually.

Epson FastFoto 680W is what most people use for scanning their collections which scans the fronts and backs at the same time.

(For flatbed scanning, I actually made a Mac app to help scan fronts with backs, lol. https://timelinescan.com/frontback-scanner [it's not as refined yet])

Getting handwriting from the back along with a potential date make scanning the backs worth it, for me, on a flatbed.