When controlling approach, if you know they’re going to be late on the intercept, use a ten or twenty degree intercept if needed. If you know they can’t make it even with a ten or twenty degree intercept, use some whippage.
You don’t have to intercept at thirty degrees, every time. Is it preferred, yes very much so. Is it required, no. You should intercept as close to
thirty degrees as possible.
Don’t be oblivious and allow late clearances if they can be avoided, be aware.
1. “10.7.4” of the ATC Manual.