I have made many batches of apple jack, and have learned a bit doing so. My first batches were low ABV, and that left a large amount of un fermented sugar available. Not only does the alcohol control the freezing temperature, but the amount of sugar also contributes to the freezing temperature. Think sorbet, lots of sugar and won't freeze solid at normal freezer temperatures. The result is a solidly proofed apple schnapps like drink. I used frozen AJC following the directions on the package, and I just guessed when it was time to make my first AJ. I have since made many batches, and some were sweeter than others when it was done. AJ will age well, and improve in flavor and smoothness. I bottled a couple of pints of the "sweeter" type back in September, and the flavor/mouthfeel is amazing. My last batch I let go completely dry before freezing, the first liquid off of the ice was very alcohol strong, crystal clear and a little short in the flavor dept, so I added FAJC right from the carton, and the flavor improved right away. The added sugar really brightens the flavor. There are so many different ways to make really tasty ciders, cisers, graffs, and perry's, and I have only scratched the surface myself.
Aging from last year: Hard Cider, Triple Chocolate Stout, American Amber II
First fermenter: American Mild
Second fermenter: Empty
Long term aging: Strong Scottish Ale, American Stout
3 new hard ciders, first is a Apple Raspberry, second will be a Apple Grape, and third Apple Cranberry. These will all become Jacked Ciders