It just doesn't seem like enough time to cook chicken? I plan to add several breasts to make enough for leftovers, increase time?

Hi Emme, even if you double or triple the recipe, I would begin checking the chicken after 2.5 hours of cooking to see if it is fully cooked. Some slow-cookers may take a little longer, and other brands may work slightly faster, so it's important to check the internal temperature of the chicken to make sure it's fully cooked. You may need to add some extra time, depending on the size of the chicken breasts you're using or the brand of your slow-cooker. Just be vigilant, if the chicken breasts overcook in the slow-cooker, their texture becomes grainy and unpleasant.