Sex with my wife probably averages 15 minutes. Some times a little shorter and some times up to 40 minutes. Quite honestly, she's in control of the time.
Over the last year, our sex has primarily taken place between 1:00am and 3:00am. - not by my choice but hers. She's always been a night owl while I've been conditioned to 5:00am wake-up probably due to my work schedule. Even though I've been retired for nearly 12 years, I just can't break that bad habit.
At any rate, she'll come to our bedroom, shower, and then slide into bed. When she's in the mood or feeling that she needs to provide "mercy sex", she'll start playing with me until I'm erect.
Then, she'll suck my cock to ensure that it's up to "standard' and to wet it just a bit.
I'll then mount her, missionary style, and start fucking slowly, grinding, etc. My wife expertly uses her pussy to pleasure me. She alternately squeezes and relaxes her vagina while I'm sliding in-and-out and feels great on my cock. When she really gets into it, she'll grab her legs, pull them up slightly, and let me go to pound town - just flat-out fucking hard and deep.
She has a wonderful habit of playing with my balls throughout our fucking. Tickling and massaging my balls while my shaft is sliding in-and-out of her really increases my pleasure. When she's ready for me to cum, she'll reach down and flick my balls. The sharp pain causes me to erupt almost instantly.
So, it all depends on whether she wants a quickie to satisfy my "itch" or something longer to enhance her pleasure.