Objectively, the bar for performance will be the same for a specific position regardless of where the candidate is coming from.
I have worked with many successful consultants who struggled just as much as anyone else with their case prep, because they were never trained on these skills. So it makes sense that the bar is not objectively higher.
Subjectively, however, there is sometimes a bit of a higher expectation for "polish" from someone who is a current consultant,
Bottom line, prepare as well as you need to, don't look for ways to put more pressure on yourself.
Hope that helps!