Well, that's when experience comes in handy
The only experience necessary and appropriate is knowing how to use the AFM and where to get the objective obstacle data. Any suggestion that generic flying experience has much relevance for missing rocky bits during an OEI climb out is misguided at best and dangerous in general.
If you know the airport, you might as well know which "rocky bit" is restricting your departure.
He who doesn't know either explicitly or implicity (if you are putting your trust in the ops engineering section) .. shouldn't be flying heavy aircraft.
Point is which segment is relevant depends on where the critical obstacle is located for the particular takeoff ... can be segments 1, 2, 3, 4 and, if you have an old machine, maybe even 5. The oft-heard suggestion that second segment is always critical may be based on observation but is flawed logic.