The timing matters
A surplus on Monday cannot undo a missed deadline on Tuesday. Work or labour must be able to move for those hours to help.
Look at workable movement
Bring eligible work forward only when it has arrived and capacity is available. Defer work only within its completion window, checking what that creates for later days.
Review the whole plan
Compare labour, backlog and service across the horizon. A lower requirement on one day may simply shift the pressure elsewhere. The decision should account for the combined effect.