i would prefer my snake seeing my hand to go "Oh, this jerk again, whatever I'm fine" instead of "I'M GUNNA GET FOOD SOON!!!!!!" and running the risk of it striking. I mean... you would have to feed it the moment it moved for that to happen, but if you left it for 10~20 minutes in it's feeding tank you wouldn't have this issue (classical conditioning requires very short time intervals between neutral stimulus and unconditioned stimulus (your hand, the rodent)).