So if a raw data takeoff is too dangerous to practice when it's on your own terms (you choose the conditions such as weather, tiredness, lack of other distracting factors, etc.) then what makes it safe enough to be allowable when you just showed up to a cockpit on leg 4 to discover a yellow sticker on the FCP and it's go-time, and you are about to do this for your first time ever?

This is bizarre.