The more the better in my book. I can move on relatively quickly but I enjoy sex the most when it's preceded by some intense foreplay beforehand. My partner on the other hand is usually more down to business, it's not that she hates foreplay, she just tends to like to get to the "main act" sooner.
I need a lot of foreplay most of the time. Although, I haven't had a partner in quite a while, so the time limit may have gone down a bit. I'd still require that we get to know each others bodies before fucking.
How much foreplay do you require before you are ready to move on to sex?
I will say 11-20 but it really depends on when the last time I masturbated was, when the last time I had sex was and how horny I am. If it has been awhile since I got off it can take 10 minutes or less. If I recently masturbated or had sex it takes a bit longer