I have gotten 5 souls once from the 50/7 map, so I don't think the 5x souls are guaranteed. Usually it's either 5/5 or 5/3 or 5/5/3 for me yesterday, but today's drops have been pretty lackluster. Unless you are in need of plat fairies and archers, running the 80/9 map would be better since the 15 souls are guaranteed there.
Are you using this to calculate how much SC you would spend? http://zenith6.github.io/aigistools/...bjective=1500#