It runs almost on all installations, though some customers don’t know what it does.
Platform Search – enables you to search content within the BI platform repository (Admin Guide).
If you use it, the general recommendation: have it scheduled instead of crawling and don’t index documents' content.
In both cases, if you run it or not, check indexing files.
You can find thousands of them, sometimes taking over 50% of CMS objects!
Run Index Rebuild to get rid of them.
Example: 33k index files of 2.7 GB