Yeah, I always do a couple (read: maybe five or six) projects at the same time, so as soon as I feel like I'm just pushing through and not being inspired enough to do my absolute best I put that project aside and pick up a different one to work on for a while.
Well to be honest I do the exact same thing!
At the moment I'm working on 3 projects simultaneously and mix them all the time, just paint the one I want and when I feel bored or not motivated - I just switch to one of the other two!
It's alright to feel burned out and not really that motivated. Just find a way to continue and you will become a bigger painter because you can motivate yourself.
For example, before the Golden Demon in February this year I had only a few days to paint 10 Goliath Gangers but I knew that I absolutely have to and I forced myself, painted after work till 3-4 in the morning and the result wasnt disappointing at all as I've come away with a Gold Demon
Keep on working mate and show us your results in the WIP section!
Best regards,
Mamikon