One thing to realize, and you just proved is that you can't compare one brew to another. No two fermentations are exactly the same.
When we are dealing with living creatures, there is a wild card factor in play..Just like with other animals, including humans...No two behave the same.
You can split a batch in half put them in 2 identical carboys, and pitch equal amounts of yeast from the same starter...and have them act completely differently...for some reason on a subatomic level...think about it...yeasties are small...1 degree difference in temp to us, could be a 50 degree difference to them...one fermenter can be a couple degrees warmer because it's closer to a vent all the way across the room and the yeasties take off...
Someone, Grinder I think posted a pic once of 2 carboys touching each other, and one one of the carboys the krausen had formed only on the side that touched the other carboy...probably reacting to the heat of the first fermentation....but it was like symbiotic or something...
With living micro-organisms there is always a wildcard factor in play...and yet the yeast rarely lets us down. So it is best just to rdwhahb and trust that they know to what they are doing.
Yeasts are like teenagers, swmbos, and humans in general, they have their own individual way of doing things.
It doesn't really matter if fermentation is "vigorous" or "not vigorous" really all that matters is whether or not we have fermentation.
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