I like to let this cook for several hours on high. It gives the flavors more time to combine together and tastes even better. I do find that this fills my slow cooker all the way to the top, so I usually have to dip out a little bit of the liquid to keep it from getting too bubbly. If you like your beans to be thicker, you can remove even more of the liquid. The consistency does not change much while cooking. You can easily put all of the ingredients together in your slow cooker at night before going to bed, but put the crock in the refrigerator (or the whole slow cooker if it's not removable). Before going to work, remove the crock from the refrigerator, plug in the slow cooker, and you're house will be filled with all kinds of yummy aroma when you get home from work.
If you're not a slow cooker type of person, no problem. This recipe was originally made in the oven. Use a large oven-safe casserole dish and spray with nonstick cooking spray before putting all of the ingredients into it. Back at 400* until bubbly.