Now take into consideration that the Indexing requires configuration on the scheduled tasks on your server to trigger the Scheduler on SuiteCRM. Check for more information here: https://docs.suitecrm.com/developer/scheduled-tasks/
Based on my experience is best to modify the scheduler to run on out-office hours because it uses a lot of system resources and it can affect the overall system usability.
IF you find your index is not working properly you might need to Reindex everything by following this tutorial: https://pgorod.github.io/Reindex-AOD/