I think his point was that the time to check the lane over is before you initiate a lane change, not after. About the only reason to initiate a lane change with

I think his point was that the time to check the lane over is before you initiate a lane change, not after. About the only reason to initiate a lane change without pre-checking where you're going is if there's an emergency (like the incident we're discussing) and then it's questionable whether it's better to do the lane change anyway...