Any practice is good. I like your idea since you'de get immediate feedback on whether if you braze on one side the metal flows through and wets the opposite side of the joint. Try different angles too, as when you are joining tubing the crotches act differently from the sides.
Actually I just might do this but work on less than 90 degree joints (as the acute angle crotch on the seat cluster is my trouble spot.)
One thing that you might find different is the way the flame "flows" and bends around tubing is going to be different from the way the flame splashes out when it hits a flat plate. So when you go back to tubing you'll need to work on finding torch positioning that works best.
Last edited by zzyzx_xyzzy; 02-03-10 at 06:24 PM.