Welcome aboard all 
I'm aware that 25% is the stat that is quoted for chance of conception per month in normally fertile couples...it seems like such a low figure 
I don't see any harm in having sex more regularly, every day if you want to-- entirely up to you and what works for your relationship, I found this below on some late night googling...
"The finding, presented at the 2007 American Society for Reproductive Medicines Annual Conference, and which is of particular significance to couples facing challenges of conceiving, suggested that daily sex could increase the quantity of sperm produced and improve the chances of pregnancy.
The research, which suggested that sperm sitting in the body accumulates damage as it ages, indicated that if sperm is released in a steady stream, due to steady sex, the sperm that is ejaculated contains newer and less-damaged cells.
Australian researchers, looking at the sperm quality in more than 40 men whose wives had either failed to get pregnant through Invitro fertilisation(IVF) or had repeatedly miscarried, found that when the men had no sex for three days, their sperm contained high levels of DNA damage. Ironically, on testing the men after having sex every day for a week, the amount of damage dropped by a third.
Dr Abisola Abisoye-Ogunniyan, an embryologist, in an edition of Fertility Update, a publication by The Bridge Clinic, stated the significance of semen quality in couples facing challenges of conception.
According to the expert, one day of abstinence can cause at least 20 per cent reduction in the sperm count. So the longer the period of abstinence from sex, the poorer the sperm count.
He added: ?But with sex at least three to four times a week, the chances of getting pregnant is higher if they meet that once a week or say at weekends.?
And then despite this there are studies showing how strong a factor stress is 
I think if you spent long enough on the Internet you could find evidence either way , they also say don't dtd every day for longer than a week because it can adversely affect sperm count
I think you could drive yourself mad looking at stats on the Internet ... So my opinion is just to do what feel right for you and your partner 