I agree, that should work. Every Shimano tech doc I've looked at with relation to indexing setup says to adjust so that the second smallest cog is the silky smoothest. I find that with older components who's pivots and such may be a little worn that getting the best location in the center-most cog spreads any indexing error over a smaller number of cogs...making it more precise throughout the range. Adjusting to the second smallest really magnifies any error or slop by the time you get to the biggest cog.