I would be working on the assumption that the 2nd check is required and plan accordingly. If when you arrive at the 2nd check a decision is taken that it's not required for you it's a bonus. But you can't assume anything about security protocols, you might get the full works whilst everyone else doesn't. And as for finding anything about decisions to not require certain checks written down - good luck with that, you wouldn't want to make it easy for those who wish to bypass security to have an easy time of it, would you?​