As part of my early pregnancy reading I've just started this book, which is about busting the myths around conception, pregnancy and childbirth, and looking at the actual facts and evidence. The first few chapters are about ttc, and she looks at the facts around how many times you should be having sex in your fertile window. She discusses a number of studies that show that having sex every day does not increase your chance of conceiving - in fact those who have sex every day have the exact same chances of conceiving as those who have sex every 2 days or every 3 days, covering their fertile window. Just wanted to share because I see this question pop up a lot and it's nice to look at the science behind it. I also really recommend the book, so far it's great.