I voted on a few of them, as over the years I have used a few methods. My experiences are pretty similar to those of OldMan47, years ago the only known cycling method was a traditional cycle with a few hardy fish.
So I have a couple of tanks that were cycled with fish, a couple fishless, the rest cloned. I think cloning is something folks with multiple tanks do on a regular basis, at least in my experiences. No adding ammonia, no testing, just divide up the mature media & fish between a couple of tanks, and go with it.
Cloning basicaly works on the idea that your bio media, when cycled & mature, will support a certain bio load. Let's use an imaginary 10 gallon tank for an example, with 10 neons, and 10 cubic inches of mature bio media. Half the media will support half the fish, so you could take half of each, put them in another tank, and be reasonably sure you will not have any cycling problems.
Mature nitrifying bacteria are capable of doubling in 24 hours. So after a couple of days you could add a few more neons, or a similar bio load, to our imaginary tanks. I do suggest testing the first couple of times anyone tries this, as well as feeding lightly, as less food means less waste produced.
This is one of the reasons folks run spare filters. I run multiple filters in many tanks, and think nothing of pulling out a spare filter, setting up a tank, and adding fish I have acquired right away. Fast the donor tank for a day or two, feed lightly for the next week, no problems. When I shut a tank down, as is often the case early in summer, the filter goes into a stocked tank.
I have yet to use any supplement or additive for cycling, I trust my media more than a product where I have no control over the shipping, handling, or storage.
Did you add ammonia or something afterwards and watch it get eaten then turn into NO2 then to N03? Or do you not do this with the product you used?
