I spent some time searching the archives without much luck (however I am always amazed at the info that a search dredges up!!).QUOTE]
To whit, I use the emergence time to estimate the status of my print developer. After my developer is tuned up, I note the time it takes for any perceptible image to show. I file this in my head. When the emergence time get too long, I figure my developer is starting to poop out. Typical example would be early on emergence time of say 35-seconds. After several prints have been dragged through the soup, I might start seeing it creep up to 45-seconds. As the developer continues, the emergence time will slowly increase. I make a judgment call and dump my developer (or tweak it with a little more unused developer).
Some photogs get more precise and use a Factoral System. For those interested in his system, youll find it in Eddie Ephraums book, Gradient Light - the art and craft of using variable contrast paper, published by AMPHOTO.