That shows a lack of knowledge of the history of 35mm and the discussion of labs. The four frame strip convention dates from way before the adoption of the more modern 12/24/36x roll length pattern. For a long time, the pattern was 20 & 36 exposure lengths, no 12 or 24. This dominated the post-WWII through mid-'70s period.
The original Kodachrome, a slide film so not directly part of this discussion, came in shorter lengths (8 exposure ?) at first because of its expense and only later in longer rolls. It was never returned as cut strips. It was originally returned as an uncut roll and later as mounted slides. In later years, boxes of mounted slides, Kodachrome or Ektachrome, would contain a few unmounted images when those images were misspaced preventing automated mounting. When this occured, the film was either left uncut or, if the unmountable images could be cut shorter, they would be cut to 2 frame strips to fit the box. The strip length was chosen to fit the existing package just as the four frame negative strip was chosen to fit the existing package.