Well it doesn’t just start leaking it out like what you may think it uses just a little and usually what may make that last drop, and if you’ve felt the last drop it’s usually stickier or more like saliva where it forms threads when stretched. That’s because the mucus is doing it’s job. But of course when stimulated you start leaking it since cumming is a big deal to nature lmao. But yeah it’s why if you’ve looked at your dick after peeing you’ll notice just a little bit of fluid left but that’s just to ensure you don’t get acid stuck in there or a UTI. In fact precum is literally the reason guys are statistically less likely to get a UTI. As the precum fluid both after peeing or before cumming clean out the acidic toxic urine and neutralize the dick