In fact, everyone who likes leg warmers expects them to be versatile. Many people like to wear leg warmers while doing chores, they are neither hot nor cold, there is no constraint and they are very comfortable. There are also sporty people who wear them over leggings or cycling pants when hiking and riding to better protect their knees from the temperature. Even walking around the house on weekends in leg warmers is a very free feeling. In this scenario, the mere 20 inch length limits these leg warmers to a variety of matching options.
A truly suitable leg warmers will be more than 26 inches long. Such a length can stay very comfortably on the calf through the natural pleats and is very relaxed and comfortable. They can also have more length to stretch to the ankle or even wrap around the entire bottom of the foot when you need it. If you just want to lay quietly on the couch and watch some TV or read, then leg warmers will be much more comfortable than the pants + socks combination. They can always go up above the knee and even thigh high when you need to protect your knees, like on rides and hikes. They are true leg warmers, not calf warmers, and it's important to note that the length of leg warmers can't be fixed by stretching them, because the ends of leg warmers don't bind too much, so they retract quickly after being stretched, and the natural length of leg warmers is actually their true In fact, the natural length of leg warmers is their true length.
So for really high quality leg warmers, the optimal length is from ankle to knee high, not just calf high.