In the time in between I had tended to finish any slightly-too-big batch of filler by going upstairs and smoothing out the plasterer's work (they had used plaster, not skim) so it was almost ready for paint. I did one more round of filler and the smoothing thereof, and then get my paint brush out. And in low light you now don't see the scars at all! I'll find out how inconspicuous it is on a bright sunny day. But I'm happy for now with how much tidier it looks!
Two sockets, an ex-socket and a light switch in view, and nothing gives away that recently, they were accompanied by big holes in the wall (except the paint not being dry yet on where the socket used to be below the radiator)