I may have got the wrong end of a stick here but i'm under the impression that received wisdom says you cannot sensibly conduct film speed and development tests across formats - that is, testing say HP5 on 35mm would not yield the same results as HP5 on 10x8. This seems to be borne out by the different developing times listed in things like the digitaltruth massive development chart.
The only reason i can think of for this would be the difference in agitation used in developing different formats because, surely, the emulsion is the same? But does it really make that much difference?
I'm proceeding slowly into 10x8 and am concerned about doing tests on film that is over £4 per sheet. I know everyone will say that using film for tests will save me money in the long run through reduced wastage but I'd still rather test a reel of 35mm/120 and use the results for the big stuff.
Is there a right end to this stick?