What is your SLA?

Our target SLA is 99.5% excluding maintenance windows.
Locally cached packages are not affected by maintenance windows (dart pub get caches all packages automatically).
We have a weekly 1-hour maintenance window scheduled for Tuesdays 10 am + GMT +10 which is used for updates requiring database upgrades. Updates usually take less than 3 minutes.
As required outages to apply critical security patches or issues affecting a significant no. of users.
We are working towards an upgrade process that requires zero downtime.