I was planning to take the third approach, although as I read the instructions it doesn't mention extending the time. E.g. using a 960ml tank it says I can process 8 rolls of 35mm, 36 frame film. A Paterson 3 roll tank holds about one litre so I would pour in 1L and process the first 3 rolls, then pour the used dev back in the bottle. As far as I can see I could then use the same one litre to immediately process another 3 rolls and then another two after that with no time extension.
They also write that more than the recommended 8 rolls can be processed as long as it's done within the first few days while the chemistry is fresh. They basically just suggest that you keep an eye on the results and stop when you no longer like them.