And if you arrange them by the use rate, it would be BAT54S, BAT54C, BAT54A, BAT54. And there is a huge gap between the first two and the last two.
The single version makes no sense to me. It is also available in a smaller 2-pin package, so there is no reason to use this package. And if you just need one diode, but already have any other type in the design, you might as well use that and eliminate a BOM item. The price difference between them is insignificant unless you need millions. But then smaller package is even cheaper.