Is she a Firefox user too, then? I feel handicapped in Chromium browsers when middle-clicking does fuck all. If it's more than three wheel spins away, I too engage "auto-scroll", as it's called. Of course you can also scroll fast if your mouse wheel unlocks and spins freely but with the middle click auto-scroll, you can also go slow and indefinitely, which can be handy for longer reads or for presentation / screen share purposes.