If BW asked me to type in my Master Password every 5 days (regardless of what other authentication methods there are), it would mean that I would be unlikely to ever forget it, without adding too much friction to the login process.
PIN and fingerprint make logging in very quick and easy, but it can make it too easy to forget the master password.
Some people won’t want the functionality, so I guess the UI should be a toggle, as well as perhaps a frequency slider going between every one days/login to every 30 days/login.