I set the padlock aside and set up both cylinders with two pins and worked on them for a while; then progressed to three, four, and five after I was consistently able to open them within a few minutes. After a while of picking the 5-pin cylinders, I tried my hand at the padlock. This all started at about 6pm tonight -- 10 hours ago or so. (Can you tell I was having fun?)
The locks I've been working have "quirks" that, having worked with them each for a few hours, I've learned to use to my advantage -- for example, one of my Kwikset clone cylinders seems to have a sticky 1st (5th? whichever is closest to the face plate) key pin, which inevitably will bind itself while I'm trying to pick the pins toward the back of the cylinder. However, I've found that I can set the first three pins in the sequence, binding the first key pin in the process, then very slightly release tension on the wrench, and the first key pin will unbind itself and, hey presto!, the lock is open, even though there're two pins I never (intentionally) set.
My Masterlock No. 140 padlock has a similar quirk; I set pin 2, then pin 4, then merely place my pick in a certain position (that I've learned completely by accident) and slightly release tension on the wrench, and the pins fall into place and the lock opens.
Am I just lucky? Or are my locks trash? I'm concerned that I'm learning the quirks rather than the art -- though, I suppose, if I can learn the quirks quickly enough when I'm faced with a lock I've never seen, I guess that wouldn't necessarily be a *bad* thing. Are occurrences like these common?
(Sorry for the long-winded post. My thanks to anyone who actually reads down this far.

-b