1.) My hi/low setting probably doesn't match your hi/low setting. From the get go, we're cooking the same meal at two different temperatures.
2.) A lot of recipes seem to call for low setting for 8 hours. This works well for a lot of people with a standard American work day, since a stew/soup will stay above safe warming temperature in a nearly sealed pot. However, the cook times are too long. Thawed chicken for 8 hours on low almost never turns out with the right texture. In this case, it's convenience > taste.
3.) The flavor is cooked out of the ingredients, and/or there isn't enough seasoning or too many ingredients. When you get the seasoning right, too long of a cook time can dull the flavor. When there isn't enough seasoning, then your meal is bland from the start. When there are too many herbs and spices, you get a mish-mash of flavors that are all competing for attention. There was an article on here a long while ago that categorized foods into low and high amplitude flavors. Something sharply distinctive was high amplitude (think nacho cheese Doritos), while a low amplitude food had weak, hard to discern flavors (plain grits). Too many different ingredients can lead to low amplitude foods, and when I see an ingredient list with 15 different herbs and spices, I almost always steer clear.
Brown a flank steak in a pan. We're not sealing in juices - we're making a crust. Throw it in the slow cooker for a few hours. Check to make sure it's tender. Prep some veggies by cutting and portioning them in containers. Find a stew sauce that's simple. When you're ready to eat, saute your veggies in a little oil, and add a generous portion of sauce when your stir fry is near complete. Throw in the meat towards to end to heat. Serve over potatoes or rice or something simple.
While it does double as a slow cooker, I have never actually used that functionality.