Thanks, Teddy! Below is the quote from that page. To me, it says we don't really know if the group took the time to lay spruce branches, or chose the quicker ski platform method.
Askinadzi on setting up a tent in winter (from my private mail exchange):
It is at the sole discretion of the leader of the group if to put up a tent on skis or spruce branches. In winter when the days are short, sometimes there’s not enough time to set up a good camp (we arrived at the end point late). This is where you need to show power! Setting up a tent on skis takes much less time than on spruce branches, but there are some nuances - does the group have enough warm clothes to lay for insulation?
If the leader decided, and he had the opportunity, to put up a tent on the spruce branches, it means he had enough daylight for this. But, in this case, he must either be an alpha leader or a the group to work well together. Setting up a tent on spruce branches will take much longer than with skis. At least half of the group will be diverted to this activity. If the hike is multi-day, the leader, even before setting out on the route, decides who will set up the tent(s), so that people know their job (this is practiced in training hikes) and, without a command, take axes and go to harvest spruce branches. Skis were sometimes placed under spruce branches when there was not enough spruce branches.