It got better, actually.
Once the install immediately after the reboot finished, I logged in. Then the machine told me it had some updates to make after I logged in. That took so long I went down to dinner and found it finished when I came back.
So, to be clear:
- Start update well before lunch
- Finish update after dinner
I wasn’t actually tracking the time at the end, but I think 5–6 hours is about the total time this set of updates took, between Avast and Windows.
How a user experience can get that bad I am honestly not certain. Somewhere in Redmond there must be someone whose job it is to catch things like this and say “no, we have to do better”, but if that person exists they missed my case.