I think it was just the natural evolution of things. Western Cartridge Co. had led the way in introducing progressive burning smokeless powder to shotgun shells with the 1922 introduction of their Super-X loads in 2 3/4 inch 12- and 20-gauge Field shells.

The next year they added a 16-gauge Super-X load in their 2 9/16 inch Field shell, and a bit later the 12-gauge 3-inch Super-X load put up in their Record shell.

By 1926, Western had added the .410-bore Super-X load and had breathed new life in the moribund 10-gauge by introducing the 2 7/8 inch Super-Ten load with 1 5/8 ounces of shot, a terrific increase over the previous maximum 10-gauge loads of 4 1/4 drams of bulk smokeless powder and 1 1/4 ounces of shot or 32 grains of dense smokeless powder, such as Ballistite or Infallible, and 1 1/4 ounces of shot!! By this time only Parker Bros. and Ithaca Gun Co. were offering 10-gauge guns in North America. About 1928, Western Cartridge Co. introduced their copper plated Lubaloy shot. The Lubaloy Super-X loads were all put up in their high brass Record shell. Also about that time they added the seal-tite wads for which they held a couple of patents. By early 1931, Western added their Super-X 28-gauge shell with 3/4 ounce of shot, put up in their 2 7/8 inch Field shell. In the first printing of their 1932 catalogue, Ithaca Gun Co. again listed 28-gauge
doubles, which had been dropped from their offerings with the introduction of the NID and the .410-bore in 1926.

So, I would say that the introduction of the Magnum-Ten in the 3 1/2 inch case, was just the next step in evolution. The first listing I have for the Magnum-Ten shell is in the April 1, 1932,
Western Ammunition for Rifle, Revolver and Shotgun booklet. The Magnum-Ten Ithaca NID double appears in the second printing of the 1932 Ithaca Gun Co. catalogue. One would assume that this project with Ithaca was in the works before the Olins rescued Winchester out of receivership.
Evolution continued. By late 1933, the 3-inch .410-bore shell was introduced along with the Winchester Model 42 pump gun. In 1935 the 12-gauge 3-inch Magnum shell with 1 5/8 ounces of shot was introduced along with the Winchester Model 12 Heavy Duck gun. During the mid-1930s Western's Super-X evolved from being a load put up in either their Field or Record shell to being a Super-X shell. Though, the 3-inch 12-gauges and all the Lubaloy loads continued in the Record case up to at least WW-II.

