For my environment :-
I run TRCASPBAL once a week during my prime shift for 10 hours to gather statistics. I then run STRASPBAL with the *USAGE option later the same day when it’s quiet – on my system this hardly takes any time at all which I’m assuming means my disks are well balanced !
I run STRDSKRGZ once a week on a Sunday afternoon when it’s quiet again and on my system it takes under an hour.
All of the above is achieved via WRKJOBSCDE.
Runtimes and requireemnts on your system may well be different but all these commands do not need to run in a restricted state.
I just read the online help on the iSeries itself.
Hope that throws some light on the subject.