Even though there is some reason for a woman to wait seven clean days, but that this depends on a custom brought in the Gemara that ''the daughters of Israel wait seven clean days even for a drop like a mustard seed'' is not really a good reason-- because to the Bach that means the color of mustard. A different reason would be like the the Rambam that straight nida blood [mentral cycle] and ziva [blood seen not at the regular time of seeing.]blood depend on an order of days that starts from the first time she sees blood-i.e. 7-11, 7--11,etc. But that is not the way most Rishonim count the days. To most Rishonim each time a woman sees blood starts the start of day of nida. [That means the way to count is thus. Seeing blood on one day after a regular time since the last time is the start of days of nida. And days of nida are only seven days. If she see once or twice or the whole seven days makes no difference; she goes into a natural body of water the night after the seventh day. But if she sees on the eight day, that is a small zava-- i.e., she waits one day and goes into a natural body of water. If she sees again, that is still a small zava. But if she see three times during the 11 day stretch of time after that seven starting time means she is a large zava and needs to count seven clean days.] And my general approach is that there is no reason to look for extra restrictions. If someone wants to be extra strict, that is fine. But they ought not make that seem like an obligation for everyone. [See the Ramban quoted in the Tur who counts the days in this way..]
