I do have over 10 U2F keys. Do I make sure every single one is synced with every service? No. I have 4 main ones that I try to keep synced with every service.

I do have over 10 U2F keys. Do I make sure every single one is synced with every service? No. I have 4 main ones that I try to keep synced with every service. Though I usually try to sync up a few more if I have them handy. For me those four are: Laptop (Yubikey 5C Nano) Desktop #1 (Youbikey 5 Nano) Desktop #2 (Yubikey 4 Nano) Keychain (Yubikey 5 NFC) I also have one in my work-laptop but it is only registered for work related sites. I also register some of the previously mentioned ones for my work related sites as a backup.