Then as you are doing regular maintenance 8 will probably be the better option.
If you read just on to the next paragraph it details what MAXDOP to use for upgrades, maintenance etc.
What you could do is set MAXDOP to 1 during the normal operational hours, then set it to 8 in your maintenance window and switch it back to 1 after its completed
The max degree of parallelism option is a setting that affects the entire instance of SQL Server. Microsoft Dynamics AX workloads generally perform better when intra-query parallelism is disabled. However, the upgrade process benefits from parallelism, as do activities that are used exclusively for batch jobs or maintenance. Use the following settings when the system performs maintenance activities or an upgrade:
Before an upgrade to a new release of Microsoft Dynamics AX, or before a large number of maintenance or batch activities, set max degree of parallelism to the smallest of the following values:
8
The number of physical processor cores
The number of physical processor cores per non-uniform memory access (NUMA) node
When the Microsoft Dynamics AX database is used in a production environment, set max degree of parallelism to 1.