yes this is my favorite pack. I use it all the time. If you have slob sims, just put a hamper or wash tub on the lot and they will leave dirty clothes everywhere.
If you have seasons, wake up Patchy and he will wash your clothes in the washtub.
To answer your question, I use both. I try to always place a clothes line if I don't do a washtub. Sometimes Sims will use the dryer or the clothes line or both. The maid will use both.
You will need to upgrade the washer, dryer, and clothesline and they dryer can set your house on fire if you are not careful.
You can also use fruit and flowers in the washtub and upgraded washer. So great pack to have.