MurrayMinchin said:
Actually absolute repeatability and consistency from print to print is one of the reasons divided developers were, uh, developed.
In the Dektol variant I use, nothing visible happens in Bath A, since there is no alkaline activator. The latent image simply soaks up however much of the developing agents as needed. In Bath B, the soaked up developing agents develop to exhaustion very quickly (under a minute) and then stop. When it's done, it's done. No further development can take place.
I understand from Ryuji and others that modern papers do this pretty well in one-solution developers, and that it's not as easy to leave a print in the developer for a longer time to increase contrast and density as it once was. My initial experiments with his DS-14 formula indicate that this is correct. As a one-solution developer develops more prints, however, it stands to reason that it loses some potency, say between the second and the twentieth print. Replenishment can address this, but with the divided developer, it's automatic. Bath A does not lose potency. Bath B eventually becomes exhausted, but as long as it is still working, it will develop to completion all the agent absorbed in Bath A.
I've written a longer article and given formulas in the Chemistry Recipes section of this forum.
Larry