Not sure if that’s wrong or not tbh, I use snapper instead of timeshift and I wanted /home included in the snapshots anyway (I think it let me set them up as 2 separate jobs). The reason I went with subvolumes instead of separate partitions is that I didn’t have to worry about sizing. I also know I can reinstall to my root subvolume without affecting the others, depending on the installer for your distro I don’t know how easy that is vs just having separate partitions. I played around with it in a VM for a while to see what the backup and restore process is like before I actually committed to anything!
mambabasa