Do it by the book for 150 odd pax boarding through one door and you will delay the flight by about 15 minutes. Most of the wrong aircraft scenarios are when pax have to walk from terminal to aircraft whilst boarding is taking place on adjacent stands.
I beg to differ.
I work for a low cost airline in the UK with short turn around times. I board up to four times during a duty that may be as long as 12 hours (without delays). I assure you that I check flight number, destination, date and departure airport (no seat numbers because of free seating policy) on every single boarding card that goes through my hand. I also will not stop head counting until I have the correct figure at least twice. And I rarely ever delay a flight due to either of these reasons. It can be done in the allocated time. If I have to delay a flight because of it then I would happily do so.
The only time I had a passenger for a different destination on board was down to a crew member at the other door. And it wasn't because that crew member didn't do her job properly, it was a simple human error. She was absolutely mortified. It is because I have seen people make genuine mistakes like this that I take my time to get it right....which is still no guarantee that it might not happen to me one day. After all, we are all just human. But I disagree with the attitude to not even try to get it right as it will supposedly delay the flight by 15 minutes as this is simply not true.
That's my opinion anyway.