It only takes 1 person in the pit crew taking slightly longer or "making an error" for the stop to have time artificially added to it.
To think the entire crew would need to be involved is naive.
Then do you think that person would stay in the pit crew for long if makes mistakes or is not fast enough?
This would be a one off race feature before that person would be moved away from pit crew.
This is a team sport and if one component of the team fails they have to replace or fix it!
If Mercedes really wanted to promote Rosberg into 1st position they only needed to give Lewes unbalanced wheel, or play around with ERS. No need to try and loose 1s per stop in hope that this will be enough for Nico to overtake.
@Davros and Gerry
Yes, team was/is a bit pro Bottas as they openly say in front of cameras. But even them during the race can't afford to favour one over the other as they need as much points as possible.