I have a pretty high sex drive, I think. My ideal day is a quickie in the morning before heading out to work, and then a nice long relaxed hour or two right after work, but before working out.
I've found that age is pretty secondary.
Emotional connection/brain connection is primary. I've connected well with 17 year-olds who were able to keep up with me, fuck like wild animals, and dropped many inhibitions. Likewise, I've connected well with 50 year-olds.
IMHO, if you're keeping up the shields, you're not getting truly nekkid, open, and vulnerable...your genitals are a pathway to your soul. They work without letting your partner reach the ultimate destination, just like you can hop in your car and drive around aimlessly.
The problem with being emotionally/spiritually vulnerable is that your partner can make you hurt like a motherfucker, and that pain can last a lifetime. I think it's called "character."