Originally Posted by tkamiya
tkamiya's advice to use stock for roll film is wise. The recommended 8 ounces stock solution covers 1 roll of 35mm film in a tank. Sticking to the guidelines, for you to use 1:1 you'd have to use a 16 ounce (2-reel) tank with an empty reel. I doubt anyone does that.
Not using the "specified" amount of stock solution per roll or sheet does have mild penalties that you may have to compensate for or accept.
The mild penalties you might face: You might not get rated film speed. Required development time may be longer. Not just longer times because you take them from the 1:1 column of the chart, but even longer to compensate for having used less-than-recommended amount of stock solution. jm94 mentions grain.
In practice I use D-76 1:1 and have adapted my times and speeds to the results I get.
Reusing carries a serious penalty. One day I developed three batches of film in one tray of D-76 1:1. I measured contrast index drop 15% each successive run.
I tolerate 5% variation in contrast index, and get concerned at 10% variation.
15%, and then 15% on top of that is just plain out-of-control, how are you really going to work with that kind of variation? Better to use one-shot and dump after each run.