Windows Shadow Copy

Please clarify your question.
Are you talking about dfs or other shares where the server keeps a "shadow copy"?

I just want to activate Windows Shadow Copy to get access to previous version... this will save time when users need to restore a file like from few days only.

I understand this is not a backup replacement.

So my question is if my U: drive for example, contains users documents and I want to activate the Shadow Copy then is it better to do in separate drive or this is not very important.

The duration will depend on how much space you allocate for the shadow copy retention.
https://www.petri.com/enable-shadow-copy-on-shared-folder-windows-server-2012-r2

The issue you may run into user A updates a file, user b reverts the file to a prior day.
if maintenance of documents is of a high priority a document management system that includes versioning and comparison of changes between version might be an option/consideration

The constraint of the shadow copy is space on the destination where they are stored.
when space runs low and files are large, the cycling of old files out while new ones coming in may have a short retention.
I.e. a person made a change and realized it
versus a couple of days have gone by.

What about same drive or different drive?

Thanks!