There are a couple of ways you can mark maintenance in bulk at the moment.
1. Alarms tab > top right bulk actions button > click on the button > select the monitors you want to mark for maintenance. The maintenance form will popup, you can configure in the form. In this case a 5 min time period is selected by default. However, you can alter it to any time you want.
2. You can also schedule a maintenance, if you have a preset schedules. For eg: The automated installs of patches I assume you have pre-configured time for the patches. You can during the same time schedule maintenance for the servers.
Admin > Operations > Schedule Maintenance is where you can do that.
3. The other way is to use our APIs to schedule the maintenance. You can explore the APIs here.
A feature that you may want to look at is to execute an automation just before the start of a maintenance and can run another automation post maintenance (configuration available in the Maintenance form).
Product Manager, Site24x7