Just wanted to say what I have gotten out of PFW Sketch, and the answer is, lots of things.
I am a writer, not a drawer, but the activities I did have been useful in writing as well. Any time I can look at something in a new way, I learn something, and drawing birds made me see them in ways I never thought about before, such as all the different kinds of feathers, the way different birds balance on their legs, where their eyes are, how they move (woodpeckers seem to hold still a lot longer than chickadees, for instance, when they are at a feeder). I loved learning how gorgeous turkeys can be and finding out that the feet of wading birds aren't webbed--and why they aren't.
For years I've been going to Scientific and Natural Areas to look at wildflowers, in part because they hold still while I try to identify them, unlike birds. But now I will be looking at birds, too, because I have a better idea about how to tell them apart and how to really see them. I also want to try sketching and painting the wildflowers, because I think that will also help me to see them differently. This paying attention to small details is so important to drawing, to figuring out what I am looking at, and tor writing as well. This has been a wonderful exercise in training the eye to see differently. And it's been fun. I never thought I would draw birds or be able to start to identify them.