Also works for 9-10 aircraft all on frequency on a mix of downwinds, bases, and straight-ins. It's all about picking your sequence early enough so you can give a good vector and place them in position to see each other.
Well if it works at a place that has 4 towered airports all within a 10 mile chunk of airspace, I see no reason that it wouldn't work at your facility.
Unless an aircraft is already on a straight-in, vectoring for an instrument is going to at least be an extra 3-6 miles. 3 miles extra for the base, 6 miles for a downwind. And even more wasted space if they'll turn a base on their own at 3 mile final. Places I've worked, there is absolutely no faster way to get aircraft on the ground than effective use of visuals and using them as much as possible.