I use a stainless steel restaurant pan inside the smoke box just below meat I'm smoking.
It seems like too much work to clean and sanitize the whole box inside to reuse drippings that would collect on the walls and floor.
Aluminum pan for me. I almost always keep a pan under anything I'm smoking. It keeps things cleaner. Even with a foil liner everywhere, I like to keep drips contained.
The pan under the meat works great to catch the drippings. I do find it helps to have a fat separator. With fatty meats like pork butt and brisket it makes short work of a tedious job otherwise.