Once or twice a year depending on how they look and feel in use, I only run hardtails though so no pivot points to worry about. I'm also not using a pressure washer of any kind when I wash the bike so as long as you grease things properly when reassembling that should stop the majority of water ingress even in the British winter I commute in.

Every couple weeks, or any time I'm going to was the bike with water. This is mainly because washing with water or very wet weather makes the main pivot point squeak. Probably partially because of old bearings, should replace those