After more than 3000 hours, I really appreciate flying with all modes engaged such as ALT, AIRSPEED, NAV or HDG.
From my experience, the most demanding situations where the night hovering over fishing boats for rescue. It is really a special job, scarring, frightening, impresive. But, while the job was done, it was a huge sense of relief to climb a bit, let say 500 ft and engage the AP back to the station.