Just Wondering!!

How often do you guys BD during your fertile window to get pregnant? I've know of people who do it every day and people who've done it every other day. It's always hard to time it right with me because I work days and my husband works nights, so he's usually tired after he gets home at around 11p.m. We start off going pretty good, but then we both tire out pretty fast during the week so I think I always miss my ovulation day because we've just fizzled out.