Thanks everyone for the replies.
I was reading 'Atomic Habits' by James Clear, and one of the things pointed out in the book was this group test that was once carried out.
Two groups were asked to produce the best picture they could take of the city. The first group was told they could only present one picture for consideration, while the other group was told they could take as many pictures as they wanted.
The result was the second group won out. The point is you need lots of quantity to get to quality.
Another point brought up in the book: people try to be consistent in their habits becuase they're waiting for the end goal, i.e. you go to the gym for a few days because you want that six-pack. Only many people will stop going after a few days becuase they don't have that six-pack yet. It's the six-pack that makes them happy, not the habit.
The author points out that what you really should be happy with is the fact that you went to the gym. If you want to maintain your good habits, don't look too much at the horizon. Do something every day, even if it's a little, and the horizon will come eventually.
Like Jimmy Cliff, I can see clearly now: since I started my new model, I'm back in the swing of things. I don't have to force time for model work at night. I'm back in that timeless, spaceless 'zone' when I'm working on it. I even did some work when I came home for lunch!
Sure, I could've saved the older models for practice in future, or maybe if/when the spark came back in me to resume building them. But starting a NEW MODEL was what I needed, because I'm enjoying doing the same processes for a new model that I could've done for the older models. It's just that the processes for the older models weren't as interesting to me (even though it was the same type of work).
So that's my little victory for the month. Now I'm just crafting for the sake of crafting: forget the end result. If I produce good stuff, yay! I can save it on my shelf. If I don't, at least I enjoyed the journey. And with a lot of work, I can only improve anyway.
Thanks for the time. :) And thanks again for the advice.