How to develop for NO effectively without excessive build times?

Seems you are right: patch in projects/Amlogic-ce/devices/Amlogic-no/patches/common_drivers doesn’t trigger linux package rebuild.
It must be in package folder projects/Amlogic-ce/packages/linux-drivers/amlogic/common_drivers/patches.

Which means what you wrote above is also wrong: removing linux stamp file and build linux again doesn’t apply patch either.