I would suggest providing more info to us to help us get you an answer.
Are you using a PDM system or just using a basic Windows file system? The final answer is probably the same - you do not need to change the revision level everytime you work on a file but you may choose to that if the change results in a meaningful design change.
"Best Practice" can be very elusive and mean different things. If you have a system in-place where you work, "best practice" would mean either following it or making needed changes to the system. If there is no system, I would suggest "best practice" means establishing a formal system and using it.