The first real decision
Take a 100-person graduate intake at a professional-services firm. Everyone gets the same induction. The only difference: half ran their role as a simulation first.
Day one, a real task reaches two of them. For the first, this is the first time the work is theirs. They know what the manual says. They've never felt the moment where the information is incomplete and the call is still required - so they escalate, wait, and lose half a day to a decision that didn't need one.
For the second, this is familiar ground. They ran a version of it the week before, got it wrong, saw why, and ran it again. The task is new but its shape isn't. They make the call, flag their reasoning, and carry on. A manager checks the work rather than walking them through it.
Nothing separates these two on paper - same degree, same induction. One of them had already done the work.