My progression as a carver has gone like this: When I started, I felt that if I didn't draw the pattern, the finished decoy wouldn't really be "MY" bird, plus I am insanely thick headed. After a handful of birds that looked like crap, I realized that I had no idea what a duck REALLY looked like. So I bought some pattern books, and made some decoys from them, in the process realizing they were still "my" decoys, and that no two people would carve the same bird from the same pattern anyway. Plus I modified the patterns alot, shaved off RPs, changed head directions etc. After carving 100 or so from good patterns, I had a feel for what a duck looked like, and how a decoy needed to be shaped to ride correctly, and all of the other things you learn by carving and gunning your decoys. About a year ago I started to stray from patterns again, some good, some bad, but learning from each decoy as always. My latest decoys I have drawn right on the wood....no real pattern, and I feel they are best works yet!
Oh, and I used to work as a CAD draftsman....so I did my share of decoy stuff in the office!!