I think artists get an idea and then they explore that idea until the idea is done with them. Then the next idea presents itself. In her book, Big Magic, Elizabeth Gilbert calls this being visited by genius.
I work in acrylic but I work with subject matter that is more typical of an oil painter. I thing I love most about acrylic is that I am forced to work quickly and decisively due to the quick drying time of the paint. I love great brushwork and try to describe with every mark I make on a canvas.
A couple of years ago I got a copy of Carol Marine's book, Daily Painting. I started to work with the idea of doing small quick paintings of objects. I limit my time to 2 hours of less on these small pieces.
I have used this discipline of painting small and often in my painting classes. Students have found it very helpful to study basic forms of objects in the studio and then paint those same forms in the landscape.