First of all sperm usually last about 48-72hrs once they have been ejaculated, in each ejaculation there is usually hundreds of thousands of sperm, some does stay there even tho most comes back out, the cervix usually sucks the sperm up from the pool that is left. If you DTD to many times in one day the quality usually dimishes somewhat because of more immature sperm been sent out, so it could be a good idea to DTD every second day so that they can mature and top up your supply, lol.

HTH.

hugs xoxo