The reason why the test was scheduled for this time was because they were taking the reactor offline for maintenance. It was delayed for hours due to the power needs of Kyiv.

Well, this particular test was supposed to have been done before Unit 4 came online in late December 1983. But the unit was signed off as complete without the test being run in order to meet the end of year deadline. The planned shutdown in 1986 was the first real opportunity to take the unit offline to run the test as they had ~3 year cycles between maintenance shutdowns.

In normal operating situations the accident should never had happened, but given the culture and pressures at the time, it really was inevitable.

>The fundamental flaw was to get people in charge that had no idea how the reactor worked and where and why it is dangerous.

I would choose to disagree on this point. They knew how reactors worked, but the design flaws and things like the positive void coefficient were deliberately hidden from them by the designers. They disobeyed the operating instructions, but did so because they were kept from knowing why those operating guidelines were put in place, and so things like the minimum number of control rods to be kept inserted at all times appeared like an arbitrary guideline, rather than something essential for safety.

It's easy to draw conclusions based on the more complete understanding we have now, but the message at the time was that it was impossible to blow up a RBMK; it was "as safe as a samovar".