Changes to stuff like this are introduced on a cycle once every 28 days - called an "AIRAC cycle". The AIRAC is synchronized all over the world, so all the systems, charts and the like on the ground and in aircraft can be updated accordingly. Obviously there is some lead time ahead to allow for publication, distribution and update of the information and depending systems.
Imagine if it was only once a year - every change affecting more than one airspace user or aviation service provider in the world would have to be introduced together. This would in consequence mean that you could only open a new runway, introduce a departure procedure or many more things on that date.
On top of this there's a notification scheme for distributing info like non-functioning equipment, temporarily closed runways (for which you don't change maps forth and back), procedures to adhere, info about an airshow and the like. This is called a NOTAM - short for NOtice To AirMen.