Here's the thing about peeking inside: Every time you take the top off to sniff or stir, the temperature inside the pot drops 10 to 15 degrees, and
you extend the overall cooking time by 30 minutes. If you can wait until you're within an hour, or so, of the finish time, though, you're probably not going to do any damage by opening the lid.
Stephanie O'Dea, who has written four slow-cooker cookbooks, says that if, for instance, a recipe suggests a six-hour cooking time, you're likely okay checking the dish after five hours; since, by that point, the majority of the cooking is done, and the flavors are just deepening and melding.
