This is me practicing painting abstract shapes.
Lots of the problems of painting still apply even when just dealing with abstract shapes. The painter still has to consider how they will hold the brush, how they will perform the stroke and in what order. How hard or soft will the transition be from one color to another? I think it is good practice to just paint shapes like this. It can be a good warm up when they creativity is running dry.
When moving onto more "real" subjects, I see that heads, hands, buildings are just certain abstract shapes of a certain color and the practice has been worth it.