Well, if it looks like the time could be done with the normal route, you don't exactly need the cut anyway. I'm not sure how Osaka and the guys are running this (as I'm not hosting), but we actually had some long discussions about this a few years ago. We came to the conclusion that the author time
can be longer than the time limit
if it's still possible (for someone) to finish the track quickly enough.
For example, if there was a 45-60s time limit, if the authortime was 63 seconds but the world record was 58, the track would still qualify (a few years ago, that is). Not all mappers are perfect drivers and back then we thought it was fair to put this rule in - it wasn't ever written anywhere though so I'm not sure if it still applies.
But if the cut saves you like 20 seconds and you don't tell anybody, and nobody finds it, they will just drive the track and see that it's too long (in the normal route) and disqualify it. You can't really exploit the system, nobody will believe the author drives 20 secs better than the judges using the same route