Great question Robin. I generally don't enter sketch challenges because I don't know how much flexibility is built in. I am not very good at sticking to a sketch, to begin with... But then I also often do not like the many many layers that sketches often use. I also have trouble using primarily PW for sketches because all their paper is patterned and I really like the clean simple look I get with card stock. Don't get me wrong, I own every single pack of pp PW sells... I just have difficulty working with ONLY that for these MB projects.
"Find something you are passionate about and keep tremendously interested in it". Julia Child