some people can go with just ONE... so think about that
for hills i figure i can do about with THREE... 60" for uphill, 70" for flats, and 80" for downhills
if you add gears between those 3 then you have a total of FIVE which I think would be plenty for ANY condition
makes you realize how wasted these new fancy pantsy 10 speed rears are now... in actuality most of the gear ranges overlap, anyways, so you dont have that many unique gear ratios... theyre just there to prevent cross-chaining (or whatever you call it)