Sheldon Brown
is with you on that, BobbyG: " At first glance, many people look at the sprocket numbers 11-13-15-18-21-24-34 and wonder what Shimano's engineers were smoking when they came up with that setup, with a 10 tooth jump between the bottom two sprockets! In practice, this is actually a very nice arrangement, because the big jump to the 34 allows the jumps in the cruising range to be much more reasonable. If the jumps were evenly spaced, the user would often find that one gear was too low for cruising, while the next one up was too high. This type of freewheel, sometimes known as an "alpine" design, is intended to provide comfortable cruising, with the super-low gear for the tough hills. It works a lot better on the road than it looks on paper!"
Regarding the wide-range double option, Sheldon's
main ride back in the day of 5-sprocket freewheels was a 14-16-18-21-24 by 51-26 - a 96% jump up front, which of course isn't needed any more but is a bit mind-expanding.