Uh, so... much as I hate the ever expanding harem trope, this would be exactly the time to summon Sister No. Four.
Quit dickin' around and start dickin' the sisters; then, after all the other pounding is done, get to pounding the dungeon... and maybe the new American Bi girl with her girl crush Mina can get some pounding, if the mangaka is really nice.
...
Really, though; that's the point of the manga:
get stronk through bonk
So...
Call 4thSpirit, go make schmoopy-pants, enter dungeon; do not deviate from this order, otherwise it'll simply be ages before we summon her...