Holds on autopilot?

BT writes:

People do care about timeing in the holding pattern, time is set to one
minute on the inbound leg, (1.5 min at higher altitudes) to for "protected
airspace", this protected airspace is to protect you from other traffic or
terrain in a non radar enviroment.

I distinctly remember, when I was little, seeing a drawing that showed
aircraft in what appeared to be a holding pattern (an oval track
around a fix), and at different levels, with each aircraft dropping
one level on each trip around the pattern. I understood that aircraft
were "stacked" this way while waiting to land. Is that no longer
done? I don't see any mention of it in any of the sources I've
consulted. Or perhaps I remembered something incorrectly? Maybe it
was never done (?). It sounds a bit risky.

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