Does one become tahor for all purposes by using a mikvah for a single purpose? For example, if a giyores converts in the mikvah, is she then tahor for marriage? I ask because the converts I know have never been required to count seven clean days, make bedikas, etc., before going to the mikvah, and according to one thing I heard, they may even be able to tovel while menstruating (not sure about this). This would suggest the immersion is not l'chatchila kosher for taharas hamishpacha. But shouldn't a mikvah dip in theory accomplish full purity, that is, by a universal standard? Please discuss.