Perhaps I would not have minded this odd
decision on the behalf of the developers had they been able to implement even this properly, but alas for reasons unknown I was sometimes able to walk through without needing the key, while the next time I'd have to stop and rummage through my inventory once again.
At every other time, though, you're left to judge jumps entirely
on your own, which
of course means that it's actually skill based, an admirable
decision on the
developer's
behalf, especially given how popular the dull semi-automatic system has become.