I think Fly Pusher gets partly credit, for how the Katyushas operated, but still no good explanation for what the crew are doing hanging about. From the veteran page of "The Russian Battlefield", interview with Semion Aria:
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Have you seen "Katiushas" fire over open sights?
Yes, but very rarely because it was risky, and Katiushas were valuable. After all, a Katiusha completely unmasks itself when firing, it raises a large pillar of smoke. That's why we tried to fire only during the dark time. If we fired during the day, the probability of enemy hitting our position increased. That's why Katiushas didn't have stationary firing positions. They had shelters where they stood, and from which they drove out to the firing position. They left immediately after each salvo, so that there wouldn't be time for the enemy to hit them. Also, as a rule, we fired right from the wheels, without using the required supports.
(...)
How much time between salvos was needed to reload a Katiusha?
Not much at all. Maybe 15-20 minutes. A Katiusha crew consisted of 5 men. They managed quickly -- loaded and then, right before firing, inserted squibs into the shells.
Did you ever fire a second salvo from the same spot?
It happened, but rarely. Usually we tried to fire and leave. We preferred to drive away and load somewhere behind a hillock than fire again from the same spot.
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So clearly, they were not afraid of killer minks thawing out by loading before firing...