It may depend on how you define "development". I can barely spell it.
Only in one case did I "knock off" one of my own designs and that is when I designed what was to bcome the Polaaris 43. It was a twin to the Valiant 40 with 12" more freeboard. I had been told it was to be a one off. Then the client bum took the design to Taiwan and had several built without paying me a dime in royalties.
The rest of the time, while paying lots of attention to my previous designs, I started with a bare sheet of vellum with no other set of lines under it. I was brash. I always thought that "this time I'll do it better." That's what drove me. Still does.