Interesting that the ID-62 formula for the concentrated stock solution, varies both in amounts and chemicals used, when compared to the straight concentrate. But if it works, who is to complain?
I used to make all my own developers at the end of the 1970's when I was a teenager and just starting out, as there was only a very limited and costly range available locally.
Most recently, I have dipped my toe in again, with the first print developer made up being Kodak D72. I especially liked the way the formula has been offered in a 'teaspoon formula', so no scales are even required.
https://www.afterness.com/kod_d72.html
I've only used it once so far, in an open tray (as I usually use a Nova slot processor, which I will be trying it in next) so don't know its what its working life is, past an hour, which I did.
One thing that I noted though, was that it gave consistent results over an hour, even though the original temperature had dropped from 20C to about 15C, with the prints given the same time in the developer throughout the printing session.
I highly recommend it after using it and it will be interesting to see how it holds out in longer sessions. On top of that, it's quick and easy to make, so it's well worth a try, especially if you have the basic chemicals to hand already!
Terry S