I juggle things as well.
When I built for clients it was a matter of sticking with it until it was done, now I just enjoy what I am doing. I do have a number of kits which get started and then either bog down a bit or I find I am not enjoying them as much as before. I build thing to have fun and if something starts to become a chore I switch to another that I know I will have some fun with.
Some builds are long haul projects- my Zvezda ISD needs so much meticulous work that I set it aside for ones which are a less ambitious. The Special Edition B-Wing is on my table now and I have a three day weekend to enjoy it in.