I have somehow never gotten around to throwing away the box of ancient floppies I've got in a closet from ages ago, and the Windows 95b (OSR2) installation disks I made were still in it, complete with custom color printed labels I splurged on.

https://i.imgur.com/iVNVleR.jpg

The media I copied from took up 28x 3.5" HD floppy disks. It's possible they were copied from what was originally a CD-ROM. I don't remember clearly anymore.

Note: I'm not trying to refute or correct your 13-disk figure, which was clearly a different installation set, and likely original Windows 95 rather than my OSR2, which came out around 1997.

Hrmm. Seems you're right and my memory is way fuzzier than I thought. Raymond Chen also says 13 [0]. Maybe it was just my existential dread of one of the floppies having gone bad that makes me think it was more.

[0] https://devblogs.microsoft.com/oldnewthing/20050819-10/?p=34....