Sometimes having eggs sitting in a pile in the nest can encourage broodiness, so that's why I suggested leaving the eggs there. But take what I say with a grain of salt because it's based on reading, not experience, given that I've always hatched in the house. However, I have had ducks go broody (just not hatch successfully), so I do recognize the difference between play and real broodiness. It kind of depends on what you want--if you're planning to eat the eggs and don't mind waiting for them to get ready to brood, then by all means collect the eggs and wait. If you don't care about eating the eggs and you're eager for brooding and don't mind a little extra work, then I'd leave a good number in the nest every day (following the method described) and see what happens.
Hopefully someone with more experience will chime in, though, and give more guidance. This is just what I would do based on my experience and reading.