A tenant can report ninety-eight percent multi-factor authentication coverage and still be one phishable SMS code away from compromise. Coverage is necessary, but the method and the exceptions decide whether it holds.
After rollout, audit three things. First, which users still rely on SMS or voice rather than a phishing-resistant method. Second, every conditional access exclusion, because exclusions are where MFA quietly does not apply. Third, the break-glass accounts, which are the highest-value identities in the directory and the most often left without modern protection.
Treat MFA as a baseline you verify continuously, not a project you close.