If the backup partition on your RAPs are 5.0 code, you do not have to apflash them, at all.
5.0 zero touch, or backup partition provides at the Zero Touch Screen:
- Static IP addressing
- 3G support at the Zero Touch Screen
- DSL pppoe support
When an AP contacts a controller the code it downloads from the controller it is contacting takes over and the backup or zero touch partition is never used again, unless you do a factory reset.
The users who MUST do an apflash are ones who have the 3.x-RN code on their Zero Touch partition. The APs now ship from the factory with 5.x in the Zero Touch Partition.