Alex, American Standards Watch Case Company was owned by Bulova and produced cases for their early watches. They shortened it to just American Standard. You can see here that is was used by Bulova as early as 1918.
Bear in mind the American Standard Watch Company is different from American Standard Watch Case Company.
My records show that these cases went from the 'globe' to the 'shield' around 1923 which is the same year we see Bulova Watch Company kick in..
They may have supplied to other companies, but they also used them themselves.
I wouldn't say that they stopped in 1925, this case somewhat shows that they didn't.
1925 is the cut over year we have seen with the case serial number going from 15XXXXX to 5XXXXXX.
As far as I'm concerned the case is 100% Bulova as used by their early watches from about 1923 to 1925.