Yes, by either security administrators or individual users.
Security administrators can define custom planning formats for particular users through the User Profile window. They can select the user’s profile and then select the Override Planning Update Format checkbox to customize the format for a user. Or, users can customize their own planning format preferences from their User Options window. They can select the Override Planning Update Format checkbox to do so.
When the Override Planning Update Format checkbox is selected, a Select Format window can be opened from the respective windows mentioned above to control how changed values will display when a user performs planning in one of their planning views.