I should have started that sentence differently.. "all going well with no abnormal events, what is the most stressful phase of the flight?"
I'm thinking takeoff. Takeoff is the end result of many prior actions. Travel to airport, check weather, check notams, submit plan, load freight, pax briefing, load pax, seat pax, start up, warm up, preflight checks, get clearance write it down, taxi out, takeoff.
I wonder of all the pilot incapacitations, how many are around the takeoff phase...