Interesting technique, Michael...and I can see how well it can work. I still do a test strip as it seems to do the same as your "out-flanking". A large test strip (using your example) that included significant areas of the print at 12, 15 and 18 seconds tells me the same thing as doing individual prints at each time. I pick a time from the test strip and make a work print (no dodging or burning). Comparing the test strip to the work print gives me all the info I need for burning and dodging the entire print.

What ever works...

Vaughn