With our mega sized litter boxes, twice a day cleaning of the boxes, and now our reduced user base, our three litter boxes are close to underutilized.
In fact, with the latest litter change cycle, we have reduced the number of litter boxes from three to two. The third smaller box was a legacy from when we had boxes in two different rooms upstairs; both upstairs boxes have been in the same closet for months.
I'll say it was retired, but let's be honest ... we tossed it. :-)