I had to do a staircase of 6 storeys in 1977. Concrete underside of stairs and the walls. Horrible stuff to use but at 19 was fortunate to be with a gang who had more experience with the stuff. Back then most spreads used 150mm wide emulsion brushes to clean their tools off with and bonding vermiculite caused them to swell.
Couldn’t win with skimming the stuff. Same day and it blebbed. Next day had initial suction then it seemed to throw the water back. Took some elbow work to trowel out the air bubbles just as the setting colour went from pink to brown.
On my own jobs I scratch coated with bonding then floated over with browning, more manageable.
I was thinking about this problem Andy G had and I recall a similar. In winter I pva’d a painted ceiling to skim and 3 hours later it was still wet. That was a bugger to skim, just slid all over the place. s**t happens. All a learning curve.