It would depend a great deal on how you manage the controllers (in Airwave)
I use a template for all controllers and keep the management settings, AAA, and SSID details in the template. To change the NTP settings, just update one controller and import the changes to the template, or edit the template to include the changes and let Airwave update them all.
To answer how you should do it, we'll need to know how you are already managing them.