It's OK.(posted 8965 days ago)Well, in any case ...
... you may have to test it. I always remember what Ilford say in their film fact sheets: The times indicated are given for guidance, and may vary considerably depending on your specific way of doing it.
Consider this:
1) It will take longer to pour the chemistry into the tank. But it will also take longer to pour it out again. That means that development starts earlier at the bottom roll, but also ends earlier at that roll. So if you are lucky, the two effects cancel. They will, at any rate, not be very significant when the development time is long anyway. While with my small tank, I dare to use 5 minutes as the minimum development time, I would hesitate to do that with a big tank.
2) Using the large volume has the advantage of greater consistency. When you prepare a large volume of chemistry, the relative error in preparing the working solutions is usually less than that for a small volume. For example: If you have an absolute measuring uncertainty of 0,1 ml for the concentrated chemcial (the actual value depends on your equipment and your way of handling it), this will give you a relative uncertainty of 1% in 10 ml, 0,1% in 100 ml, etc.
3) I wonder if you will in fact agitate such a big tank vigourously. For two rolls of 35 mm, 500 ml of chemistry are common. That would make 2,5 litres for 10 rolls. It would certainly make a good exercise to wiggle abouta little more than 2,5 kilograms. If you observe that your agitation gets slowed down by the big mass involved, expect the result of the development to change. However, I wonder if the effect is big. Actually, agitation aims at bringing fresh developer to the heavily exposed places. In other words: by agitating, the developer is mixed again to have a uniform concentration everywhere. When you use one-minute agitation, I think the four inversions in 10 seconds suffice to have the developer mixed again to equilibrium. Therefore, as long as you stick with the four inversions in 10 seconds, there should not be too much of a difference.