I have a 7', 3 wt rod, a 7', 5 wt rod, a 7'9" 5 wt rod, two 8'6" 5 wt rods, and two 9', 5 wt rods. I fish primarily for rainbow and brook trout in mountain streams and valley creeks. I use the 7', 5 wt more than all the others combined.
I have the 7', 3 wt set up with a Cortland DT3F line, hand tied, 6', 4X leader, and 18" Orvis 4X tippet. It throws 12 and 14 nymphs. While it is by no means a primary rod, it is a specialized rod that gets use in many of the small valley creeks where a big rainbow would go 10 inches, and a rare brookie might go 7 inches.