I disagree a bit here - the only goal of saddle height- and fore/aft adjustment is to set the rider in the correct position wrt the BB, based on leg length, KOPS, comfort, efficiency, whatever one's yardstick is (I'm disregarding crank length here for simplicity, but obviously should also be considered). All other considerations are secondary. If the saddle is maxxed rearward once that ideal position is determined, then the rider should look into a seat post with more setback, or, as a last resort, a frame with a slacker seat tube angle, to achieve that saddle/BB positioning without slamming the saddle. AFTER THAT, the cockpit length should be addressed, generally through a combination of handlebar reach and/or stem length. If a comfortable cockpit can't be attained with a reasonable stem length ("reasonable" being in the eye of the beholder, of course - but I think anything in the 10-14 cm range would be reasonable). Anything outside that range would suggest that a frame with a longer/shorter top tube might be considered. What I wouldn't do is adjust saddle position to tweak cockpit length, unless it can be done without compromising that all-important saddle/BB positioning.