Sex is usually after at least 10 minutes of foreplay. I do all the foreplay, but I enjoy it so not fussed that she doesn't reciprocate. When sex goes on for more than say 5 minutes she loses interest and starts asking if I am done yet.
10 minutes foreplay would be a quickie in our book as would 5+ minutes penetrative sex. We easily spend 30 - 60 minutes on foreplay and often a lot longer. Not all of that is genital stimulation either, far from it. Lots of kissing - mouth, neck, back, feet especially, massaging and caressing. It should be a journey to be savoured and enjoyed, revisiting favourite spots but also looking for and exploring previously unknown joys. Trying new things, assessing feedback, adjusting and refining. We've been together almost 25 years and we're still discovering new things. For example, my wife has always enjoyed a head massage but a few weeks ago I happened to massage her head in a particular way that I hadn't tried before and it had her purring like a cat, so I've been exploring that technique further and trying variations. I love exploring her body (and her mind) looking for new ways to give her pleasure. It never gets boring because she is human and dynamic.
When it comes to actual sex, again, approach it every time like a special journey to be savoured and enjoyed. Don't just amble along the well-worn path. Try different positions, even subtle changes in angle, different tempos and read her responses. Use your hands, mouth and even your toes during sex to caress and tease other parts of her body. Stop thinking of it as foreplay then sex as well. It's not like a dinner where you always eat your soup and then your main course. You can take a break from the main and return to the soup. You can have main and soup at the same time. You might have so much soup you don't need a main.
Not sure where the dining analogy came from but it seemed to work so I hope it makes sense.