here i go again...

Recently i just found out that some of my fav artist used to make studies of a particular image, object previous to it's artwork, at the moment when i see it in books or museums the artwork didn't make any sense of why they do this and not going straight to the canvas..?? but is more like the way they can work in this and reducing and exploring the possibilities of it prior to paint it, and yes, i used to thought that was a useless idea but is not, is really not, so i was thinking to work on some canvas, but i need to first have an idea of how some object would work on it, like colors, light and else... well, this is what i've been doing lately as part of my artworks....