Okay...I think I get you now.
The issue is more basic: until you can redraw something you see acceptably fathfully, you should hold off on your own characters.
Your next mission, should you decide to accept it, is to practice *tracing*, copying and redrawing everything
....newspaper comics, magazine covers, novel covers, cereal boxes, family photos..anything handy. I starred (*) tracing because, really, when an artist draws something
representational, even without a physical picture, what they're doing is 'tracing' an image they see in their minds.
The good news is that right now you can see that for whatever reason(s), each time you try to redraw the same dragon, it doesn't look the same. Probably you'll redo certain details but will get sloppy on proportion and positioning. ...like, you'll try to redraw a dragon that has two horns on his/her head; you do the two horns...but they're thicker or not in the front or don't have quite the same curve or same length or the head is bigger or a more oval than round and the neck is different, etc so that in the end, its just not the same dragon, right?
Practice...you just can't skip or sidestep the hours and hours
it takes develop an eye for that...months...weeks....years
Our "jeff" is one of the best here when it comes to drawing representational/photo-realistic portraits. He has an exhibit coming up, even. But read here
how he says, he "put a few more hours in". So how long does it take for him to draw one of his exceptional portrats? Do you spend one
hour drawing a dragon?
Here's a good mantra: get good (or, work slow until you), get fast (as in, make less fundamental mistakes and/or correct mistakes faster) then get good and fast. There's no shotcut.
To (finally) answer you very first question, we've ALL had that problem, and if we're not careful or watchful of it, we can add hours of work fixing something we messed up on along the way. We press on and get it done.