From the GE CF6-80C2 Operating Instructions:
B. Duty Cycle.
(1) Starter Maximum Continuous Operation is 5 minutes
(2) Cool starter 30 seconds per minute of operation.
(3) After two consecutive 5-minute duty cycles, cool starter for 10 minutes prior to each subsequent 5-minute duty cycle.
The AMM words are not intended for 'normal' day to day engine starts - they're intended to apply to specific AMM tasks such as wet/dry motoring, leak checks, actuator tests, etc.