Holding a load in your mouth to spit it out later seems so weird to me. If you're willing to take it in your mouth but grossed out by it, swallowing is the fastest way to get rid of it. I can certainly see how some women might be turned off by the idea of having some stranger's cum inside of them (even if just GI) buuuut holding it in your mouth to spit it out later just makes you more susceptible to any germies and you'll have to deal with the taste for much longer -- think cough syrup or rail liquor...yuck.
That being said...I'm a cum-hound, so I generally keep sucking until I'm pulled off or the guy starts making pathetic "TOO MUCH" sounds at the height of sensitivity. Cum-play is by far my personal, slutty preference, but it's never something I can promise before testing out chemistry. Also...some guys have funky spunky and I don't like spoiling the fantasies associated with everyone else's cum.
(Heavy pre-cum is also super hot with the right partners since back-to-back rounds are hard to find. Sigh. Once I get a load I'm far more riled up...it's sad when things subside after his pop.enter bukkake fantasy here)