if you go thru my 650 posts prior to my stay in key west you never saw a drawing on any painting i ever did. see a scene, jump out paint it! bOOM! no thought or designing (in my head, but not on paper), just painting and hoping for the best. not the best way to do a great painting. a really good way to MAYBE get one tho'. and i did get some good ones that way but i want to make sure every one i do is the absolute best i think i can do at that time.
not to say that your painting will be great just because you think it thru, sketch it out, or plan it. but you have a waaaaay better chance of doing one if you do, right?