Well I suppose that would depend on how often you wrote and deleted to their internal disks. If you do a lot of this then maybe; but it would also depend on the OS that the NAS is running. If the units you have are not of the budget type then they may well have a pre-scheduled task to do this automatically.
If I were you I’d login to the NAS and see what utilities it has to offer regarding this, if there is nothing built-in then check the vendor’s site for available plugins to do the task but do not get Windows to do it, only defragment the drives using utilities of a compatible OS and if the OS on the NAS is Linux then I don’t think it will be an issue.
