Many years ago I heard of Mike Bailey and followed his blog. He went into working in a series and that became his thing. Now, not just 3-5 or 7-9 paintings, he challenged a student of his to do dozens of paintings using the same still-life set up and see where it took them. She stopped at the required number (I think it was 25 paintings) but he kept going...and going...and going. Now, he talks about that series and shares the paintings that came out of that experience. I’m afraid I don’t have that determination, but, in the Angela Fehr online class (Watercolor Mastery), she talked about working in a series and what you can learn from it. So...I got out a photo I liked and did a few...just a few.
A strong value study (Notan) followed by a value study with minimum color.
Then going in with lots of colors, then more muted colors (my favorite one).
I even abstracted a couple versions and might show them later.
I think I did 7 in all and then had to move on to something else. Maybe if I had started from a still-life, I would have had more enthusiasm for a long series...nah, probably not! ha ha