User blog comment:Shinhwalee/Guide to Power Leveling Heavy Cruiser (CA) in World 3-2A/@comment-5935877-20150321124219

The guy who suggested 1CA 1BBV 2DD 1CL and 1SS was me. There is nothing wrong about it beside the fact that DD and CL need to be constantly rotated, but you don't need them to be max or high leveled one. A decent DD/CL ranging from 20 (im pretty sure people will get them easily) with x2 main gun and a radar if possible (if someone is lucky enough for small radar) is enough to deal decent damage and you can also level them up without them being completely useless. Even with Red T, you can still dealing some damage without going to night battle and only 1 FS/Elite DD appear in 2/3 patterns. Plus the chance for CA getting MVP is 95~97% with almost no chance for night battle and is fairly cheap to constantly running 3-2A without losing a few 60~90 fuel and 100~150 ammo per sortie (thinks about how much rsc you can save using my compo)

TL;DR: Again, the compo is good, cheap and effective enough for multi leveling 2DD and 1CL with decent exp per run (~320 exp).