Throwing holes that leave you with a short upshot are a whole lot less useful for practicing those shots than ones that leave you with something like 150-250' upshots.
Maybe so, but they're a helluva lot more useful than throwing holes that leave you with a putt every time.
If you're struggling with 50' upshots the course isn't the place to be trying to fix that anyway.
Not every problem can be solved by field work.
I've run across plenty of people who can park 50' upshots in a field all day, every day, but put them on a course where they need to negotiate schule/trees/a narrow gap/low ceilings/other obstacles to get their upshot to the basket and they can't hit the line they need to hit to excecute the shot reliably.