I don’t see how that’s possibly valid.
My guild clears normal (which we’ve run the last few weeks just to finish off the skip and get peeps that were gone over xmas their legendaries) in roughly 2.5 hours, and that’s even with the occasional wipe as we deal with some of our bench peeps learning the fight. Each boss drops 0.15 items per person, on average (3 out of 20), which is 1.5 items per person for 10 bosses. That’s 0.01 items per minute per person.
For M+, it depends on where you’re landing on the timer. For a timed run, we can presume an average of 30-35 minutes (since all of the instances have a timer of between 30 and 41 minutes). You get 0.4 items per person, so that’s ~0.013 items per person per minute. For a failed run, presumed average 45 minutes, it’d be only ~0.0044 items per minute.
In order to get 0.12 items per minute from M+, you’d need to be completing the run in approximately 3.33 minutes total. If that’s 0.12% drop rate per minute, that only adds up to the known 40% drop rate for a timed key if the run took 333.3 minutes (~5.5 hours), which is clearly not valid, or timing the key. Raiding being 0.0004% would add up to the known 15% drop rate per kill if each boss took 37,500 minutes, or roughly 27 days.
So clearly either your memory is faulty or the original data is. In either case, the drops per time spent between timed keys and relatively efficient raid clears is similar. Progression raid nights, of course, are going to be much much slower, but so is failing keys (ie. a regular occurrence as you try to push keys higher and higher).
Edit: looking at it closer, 1.2% drop rate per minutes would make sense for M+. That’s effectively 0.012 items per minute per person, which is nearly equal to what I calculated. So that value may simply be off by an order of magnitude.
However, the raid one simply doesn’t make sense. The best I can come up with for that is presuming it actual means 0.004 items per minute, or 0.4% drop rate per minute. However, that would only be valid if clearing the raid took 2.5 times as long as my value, meaning over 6 hours to clear the 10 bosses. That’s not farm content, that’s progression.