Developer Volume -V- Time

Given the correct volume for the size of film, does the amount of development time change from 35mm to 4x5"? In other words, does it take a different time to develop a roll of 35mm than a sheet of 4X5 with the proper amount of developer for each?

The only reason I can think of that would require different developing times would be agitation differences.

If it's the same film emulsion, then the times and temps remain the same. Looking at Kodak's data sheet or other sources, you will see that the only variables are whether the film is developed in a small tank or a large tank. Agitation should be identical, given the same developing tanks.

Some people do add 10% for 120 vs 135, but I'm not one of them. I use exactly the same times and temps, and it looks fine to me.

On the bottom of my Patterson tank it has the recommendations for amounts of developer for different size films. It's just to make sure that the film is properly submerged in fluid. Development remains constant regardless of film size, as you are increasing the amount of liquid proportionally.

Short answer: same time is OK for both for practical purposes
Long answer: I'd be surprised if the CI was exactly the same due to a myriad of minor things that affect development, including but not limited to, size of the container, ratio of film surface area to tank volume and or developer volume, minor temp. variations between processing sessions, rate of filling and emptying etc, etc,....

It depends on what you do to the negative to print it.

What do you need the negative to be?

Some possible variations:
1. Do you print your 35mm negatives and 4x5 negatives to have a similar look? Do you need more contrast from one than the other?
2. Do you use different output for sheets, like platinum/palladium, or kalitypes, perhaps? If so you'll need negatives that are radically different from silver gelatin or even scanning.
3. Do you use the same enlarger for both types of negatives? Condenser and diffuse light source enlargers give slightly different results.
4. etc

Assuming you expose your negatives the same way, print them the same way, expect the same contrast from the final print, etc then the developing time should be the same. But if anything changes in how you print, either by necessity or preference, the developing time will differ.

As momus has posted above, it depends on what sort of development tank or tray you are using.

If you look through the Kodak data sheets, you will see that roll films tend to have one set of development recommendations, while sheet films tend to have another. Some of that difference is due to there being a tendency to develop roll films in small tanks with hand inversion, as compared to sheet films in larger tanks with hangers, but you will see as well that there are different recommendations for roll and sheet films for rotary tube processing.

Even if the emulsions are the same (sheet vs roll), the material that the emulsion is coated on will have an affect on how the developer and the emulsion interact.

And as Thomas has posted, your expectations of your negatives may vary between the formats.

So the answer is: "It depends"

Thank you all very much, yes, it depends. There are no simple, straight forward answers.