Process "Rebuild Learning Item Indexes": Which interval and what does it effect?

Summary

In which interval should the process "Rebuild Learning Item Indexes" run and what does the process effect?

Content

Hello all,

we have a issue regarding the process "Rebuild Learning Item Indexes".

At the moment the process runs in an interval of 5 minutes. But we have many processes running at the same time and would like to relieve the system by changing the interval of some processes. 

So our question is: In which interval should the "Rebuild Learning Item Indexes"-process work and how can we change the interval?

Maybe someone could also describe what the process exactly achieves? We found the following description: