I'd be fine with a home-console Zelda about every three years.
I need time in between them to get the craving again, and the handheld games come out inbetween the main entries too, so a two-year cicle would be too short imo, basically making it a yearly franchise. I don't wan't that fatigue with Zelda.
I expect their developement cicle to speed up, once they got used to HD developement, though so the next Zelda ight not take five years to develop.