I haven't been here in a while, but ready to jump back in. I always thought you backed off slightly because I was taught (or picked up by osmosis or whatever) that you don't get a good torque reading from a static nut.
That said, after scratching my own head a bit, I think if the goal is to make sure nothing is loose, put a wrench on it and see if it clicks. If the goal is to have as uniform as possible torque specs within standards across all nuts I would loosen and tighten back down.
Will add that in 45 years of British car ownership and lots of heads of and on with Triumphs, MGs, and Austin Healeys I have seen a lot of things break, but never had a head gasket problem. The old cast iron heads are a lot more forgiving than the modern pot metal stuff. You are probably ok doing it either way.
I will add the usual debate I see on this are is if you torque the studs dry and clean or lubed. I think ARP has information on that, but the old factory manuals, is the torque spec. for dry or lubed?