In Israel, I sell discount ovulation kits, along with telephone support - so the question as to whether to have sex every day or every-other-day during the fertile time comes up a lot. Being unable to take any sort of responsibility, I quote a doctor (who gave me permission to quote him) and say that if they don't suspect a problem with the quality of the sperm, then every day is fine too. Now it seems that even if there is a problem with the quality of the sperm, sex every day might be better than sex every-other-day.
A pilot study (see article) led by David Greening, of Sydney IVF tested 42 men whose sperm showed significant DNA damage and found that daily ejaculation reduced this damage by 12%. These results were presented at the American Society for Reproductive Medicine conference in Washington yesterday.
Abstaining from sex increases the number of sperm cells that are ejaculated - leading to the recommendation for couples who are trying to conceive to only have sex every two to three days - but the article says that beyond this time period, although the quantity may rise, its quality declines; a trade-off.
I wonder if such DNA damage is tested in a normal sperm analysis, if so, what parameters show it and how common is such damage? If it makes an important difference (knowing whether there is or isn't DNA damage), it seems like information couples should have - and may even make it sensible to have two sperm analyses day-after-day to check if the sperm quality improves.