Advice often given to would be artists is that they should focus on one style, approach or theme if they want to be taken seriously. My view is that a true creative should be willing to experiment and try new things, in fact, should be passionate about it. Saying that, developing small sets of work as series is always a good idea because it shows you can be consistent in your practice if you need to be.
I find that I work better and with more energy when I have several paintings on the go, usually with 2-3 in a set. Prevents ‘fiddling’ and over working too.
I have a few different approaches to move in and out of, sometimes focusing on colour, other times shapes or marks, or representational subjects. On my website (currently receiving some adjustments) and on my Bluethumb site you will see several series depicted.
The format of the surface often influences the end result. Rectangles in the horizontal tend to landscape, verticals to still life, forests and florals. I mostly paint in square format when doing abstract work.
Sometimes a sudden inspiration moves me to complete a single painting quickly as my seascape below using silicon tools. It is based on a segment of a photo taken at Bruny Island a few years ago. I have tried to keep it loose and free.