Only one visit was required when I renounced (Amsterdam, 2015). It may vary from consulate to consulate. Have a look on the website of the consulate you have in mind - somewhere under the "Citizens Service" section. If you don't find anything useful, email them and ask.
Commonly, once you email them requesting an appointment, they'll send instructions telling you what documentation you need to prepare and how they want you to do it (send or bring).