Would have been more believable had the first ambush failed and took one or two losses. Second ambush a little more successful...getting experience a little at a time. These guys went instantly from football hicks to elite partisans.
shareI don't think we are seeing the time pass on a day by day basis. I think they are doing these missions and then days or weeks pass before they do another one and/or they are doing missions we don't see in between. We do see them start off as clumsy and gradually get better at it. Their first couple of missions are ambushes against unprepared targets. The soldiers sight seeing were easy targets.
As we have seen in Ukraine the Russians are not very good soldiers and suffer from poor morale and training. At the time of the film it was believed they were equal to the West but it was never the case. So they wouldn't be that hard to fight.