Do you know the importance of palette to an artist? It is not about a piece of wood or surface we called a palette, with patches of colours. It is about the information on the colour scheme stored after you have done your artworks such as painting, watercolour painting etc. Watercolour is a medium that I liked most. The medium is simple, but yet it is also expensive. Sometimes it is not about the cost. We can use it over and over, and at the same time, we maintain our colour scheme.
The image below shows a palette of an impressionist painter, Monet. Through the palette, we can imagine and identify the colour scheme used by an impressionist painter. So, if you are using watercolour, do not wash your palette.