I always pour my gallons off into quart cans when
painting in pieces. If you keep taking from the top of a gallon can
little by little, the last will be different (especially metallics)
no matter how well you stir it.
Stirring well at first and pouring into separate qt cans
really keeps it more consistent and easier to use.
I even pour my primers into qt cans, just easier to work with
and it keeps better for me since I do so many "small jobs".