For most of my detailed cutting I've been using generic #11 craft knife blades and it seems the "wear curve" on them is rather aggressive to start with then kind of goes flat.
Like, a new blade goes through leather like butter but that lasts for maybe 4-5 decently sized cuts before it starts needing multiple swipes and then at some point it almost feels like the leather is bumpy or grainy where the blade isn't cutting through denser sections.
I don't want to be too wasteful nor do I want to be forever changing blades - how long do you tend to go between changes?
I think that, having never really used craft knives much, I never thought about the costs or longevity. I've had a few of those little sets that come with one blade each of a load of shapes but not really any that came with a pack of replaceable ones. The knife I've got came with 5 blades, I never even realised how cheap 100 extra blades even was...