I use them slightly differently. I use them as a 'pallet' of colors.
When I start a project, I make several finish choices, spray the spoons with them and hold them next to subassemblies like chassis, interiors and wheels. This gives a much more accurate idea what the finished project will look like rather than trying to imagine a color chip, the cap or bottle color in three dimensions.
The colors I don't use are available for other projects where the spoons help out again.