I don't think the sizes of album pages -- which vary from one manufacturer to another, so that no page seems to fit another brand of album -- are derived from larger sheets, but simply chosen by the album maker. The excess paper left over after cutting these sheets is the paper supplier's problem, I suppose. When Minkus came out with their albums in about the 1960s to compete with the existing Scott albums, I remember, they chose to use slightly different page sizes which were only off by 1/4 to 1/2 inch. Why do that? Most likely to insure that anyone who purchased a Minkus album, could not use Scott pages of any kind (including blank pages) in it. They'd have to use only Minkus pages.
Today, Schaubek pages are a different size from Lighthouse, Davo, etc. This can't be because of some larger requirement related to paper size or avoiding paper waste. It must be because the manufacturer wants their own unique page size -- plus some attention to what their designers think makes for the best layout, the best look for the album, and so on. These are elements of brand uniqueness along with design qualities, but probably not due to manufacturing qualities. But I could always be wrong.