Yes, I'd say so generally. If you move very quickly, know exactly where you are going and have priority security you can make it for airport entry to a gate... if you get lost, delayed, or hit queues you risk being late. Doors tend to close 10 mins before departure.

Also, what if the bus is 15 mins late? I didn't even know the Go busses went to the airport. If they drop you off at say the wrong terminal you are stuffed.