when pin tumbling I use a hand measured half tsp of the lemi-shine and a glop of car wash.
any more is a waste.
when just agitation washing them [mainly to get all the dirt and junk out of the cases from ground found brass] I use a tsp to a gallon but still keep the soap down to a minimum.
rinsing is optional but I do sling the cases around to get all the excess water out of them and either set them near a fan or leave them sit on an old tee shirt to dry.