I can understand your concern.
Finalizing the menu mix should happen after you've checked all the information and verified that it is correct. The menu mix is used to calculate your Ideal Usage (how much of each ingredient your location should have used for all of those sales), so finalizing the Menu Mix needs to be done to have accurate Ideal Usage information. The same principle applies to finalizing deliveries and finalizing inventory counts: these values are used to calculate Actual Usage (how much of each ingredient your location truly used).
Hope that helps!