"Industry Standards" for Data Center Maintenance Windows

I am seeking comments and white paper links on Data Center maintenance windows.  As a DC lead, I am now under a mandate that physical work is only allowed once per week during a specific window as approved by the change control board.  This window must include changes requested from all server teams.  Previously, daily work was allowed as needed with proper notification to change board.

I am also been advised that between now and sometime next year, the ability to work in the DC will be changed from once a week to once every two weeks, then three weeks and finally work will be allowed only once per month.

DC work being defined as:

1. Pulling floor panels for tracing wiring as needed.
2. Installation of drops
3. Power work ie: New power connections
4. Phone cable work
5. Security system work
6. Device installation in racks
7. New rack install
8. Etc, etc.

Emergencies are on an as needed basis to keep the lights on.

Can anyone provide and "Industry Standard" for DC maintenance windows?  

Thanks.