My deployments have been every five years thus far. I'm a senior officer within the communications branch. The number of positions for communicators at my rank level is limited, so I don't get deployed nearly as often as a soldier would, like an infanteer, a private, a master corporal, or even as much as within the limited trades, within the logistics world, or within even the communications world where we have limited numbers of linemen. A lineman can actually be away for the majority of his time, whether deployed within Canada or internationally. So it really varies depending on the rank level and the trade.
Honestly, for me it's every five years. I'm just coming up to the two-and-a-half year point that I've been away, since Anne and I have been together, but for other people it's much more.