thats cool bro, but i promise that all 10,000 of your employees will NOT be using a password manager and enforcing a rule where they have to would be stupid and add unnecessary complexity. (and 9,950 of them will only use your companies password in it anyway.
change once a year, maybe once every 6 months if user security is that high on the totem pole, use two factor if feasible, and dont allow reuse or simple passwords.
realistically most hacking situations involving user passwords being compromised happened because they reused it on something you DONT control (some bs website that got their db dumped, their cellphone, w/e) and in that case what really matters is UAC and ensuring the rest of your network is up to par.