I was fortunate to score 4 bricks of 45 year old Kodak Plus-x 35mm recently. I was already to trim a roll to fit my Leica IIIG when I discovered that the leader on the film just fit? Did leaders become shorter? I am still experimenting. These photos were developed in Kodak HC-110 dilution B with benzotriazole added. The photo of the barn door was taken with my Kodak Signet 35.
The leaders, i.e. the leading portion of the film that does not take a picture, are the same length. More of the leader was cut away in earlier times to work with bottom loaded cameras. It is a myth that usable film is sacrificed when modern film with a shorter cutaway is trimmed to work with the older cameras.
I have a few b&w rolls of film (from the 50's to 80's) that have the long leader like that, the rolls I have from the 90's onward have the usual, shorter leader length.
For a couple of those rolls I shot I had to cut down the leader a bit, they didnt fully catch when I put them in my af camera take-up spool