Every year I plan on painting the Dark Elf Sorceress from Games Workshop. Most years I fail. Most years I just forget about it and move on. Having said that it seems that every 5 years I actually sit down and do it.
Here are the 3 attempts that I have done.
2015
2018
I don't think that I have improved that much but that lines up with my slump in painting. The challenge is to see what can be achieved in 2 hours. I think this is a great test of your skills and what can be achieved in a strict time frame. As you can see in the 2018 and 2023 pictures I have done more work on the face and skin than in the original from 2015 but the one from 2015 is finished unlike the other 2.
Anyways just sharing this idea. Maybe give it a go and see how your paint style changes or improves over time.