I’ve noticed that not many people have enabled the Rebuild Indexes site maintenance task. ConfigMgr administrators are either unaware that this site maintenance task isn’t enabled by default, or do not understand the importance of this task.
The reason it is an important task to run on your ConfigMgr site server is because it allows you to get the most out of SQL Server when it is being queried by the ConfigMgr console, reports, collections, etc. For more details about SQL indexing see my blog post entitled, “Why is SQL Server Indexing Important?” By the way, I think this task should be enabled by default, but that’s another story.
To enable this task, open the ConfigMgr Console and select the Administration bar. Next, expand the Site Configuration node and then select Sites. In the ribbon bar, click on Site Maintenance.
Select the Rebuild Indexes item and click the Edit… button.
Select the Enable this task check box, select the appropriate days of the week (I like daily) and finally select a start and stop time. Due to all of the other tasks that are enabled, I always select a random time between midnight and 5 a.m., but never on the quarter hour. This helps ensure that it is the only maintenance task running at that time. Click OK to finish enabling this maintenance task.
If you have any questions, please feel free to contact me at @GarthMJ.

Hi. We have enabled this on numerous servers and cannot see it executing. We are looking at the SMSDBMON.LOG and constantly sees this “Added Task for Rebuild Indexes (task off)”.
Is there anything else we can do\look at from a log point of view?
We are contemplating on using the OLA scripts and doing this form SQL.
I would go with Ola Script. https://www.enhansoft.com/installation-guide-to-ola-hallengrens-sql-server-maintenance-solution/