Keith hits the nail on the head, and it gets worse aswel. In a good, satisfying way..
You have managed to put a good base coat on. Then comes the moment where you have to add a second coat, either camouflage or to shade.  For me that is the 'ooooooohhhhh' moment.. all that work you have done, and it's looking good, and then you might ruin it all with your next step..  
 Example, my latest creation. I painted the base coat, dunkelgelb. Fine, basic, no problem. Then came the green squigels. Aaahh free hand, will it work? Not quite, to much over spray.. 

 . Fine, no panic, lets overspray the overspray with dunkelgelb. And than touch up with Green, and touch up with gelb again... you get the idea.
I was happy enough with the way the green squuigels worked, but then looked at it for a day and knew I had to add the red brown spots... 
 The moment with my AB loaded with red brown paint, pointing at a model that would have been o.k. if I left it, risking ruining all with the first spray... 

It never goes away. Keith says that he still has it after 20 years..But the satisfaction of the end result makes it worth it, every time.
Practice makes perfect, ( who am I kidding 
 :-) )
Cheers
Henk