I always try to pick first, even if I know the lock is tighter tolerance. You never know, you might get lucky. Sometimes I may have the customer walk around and check for other unlocked openings, but it's mostly to keep them and their kids away from me while I work. If picking doesn't work then I will do my own walk around to double check. I usually only charge for the trip if it only takes a few minutes (5-10 minutes) to get them in but anything over 15 minutes and they start paying for it. So they got what they paid for if they happen to find an unlocked entrance...
Personally, and maybe it's just me, I always feel like a failure if I have to destroy a lock. Especially a simple one. But around my area, they are almost always installed upside down (bible on the bottom). Must be the Carpenters Curse... Anyways, I find that the pins tend to sag on the springs and it makes the shear line next to impossible to find as the pins are mostly below it now. You can drill it, or use a small finishing nail or pin and knock the first pin stack down removing the spring cap. When the rest of the pins fall out then any key blank that will fit will work. You may have to dress the key-way a bit if it was damaged by the pin but they are usually save-able. Then I charge to rekey.