Corner marshalling? Yup!
When you first get to the track of your favorite Annual, Super, or Mega event there’s likely a new fresh layout to get accustomed to. Once I’ve found my pit area, setup my pit and got my packs charging, tires gluing, etc etc I will take a moment to stand track side and watch the cars for a few minutes. Take a mental note of the sections that others are already having an issue with and see what they’re doing wrong, from the track level.
Once you’ve gotten some time on the track you may find that the “trouble” section you were seeing earlier isn’t something you’re having issues with but perhaps after the first qualifier you’re struggling with a section that was clear in open practice, but now must be approached differently in traffic. Make it a point to corner marshall that area. You’re already supposed to be watching the area while marshalling, so take advantage of that time and see what others are doing better than you in that area and apply that knowledge on your next round!