How to answer "Situational" Questions?

Something I noticed now is that it is no longer strictly behavioral and technical questions, but also situational questions thrown into interviews as well. So now instead of getting the typical "tell me about a time when" questions where it's really easy to have your STAR scripts ready to go, now we get questions like:

If you notice a presentation that your MD is using for a meeting tomorrow has a mistake in it, what do you do? What would you do if you were given too many tasks work on and couldn't complete them in time? A client calls and is very demanding of X, but your superior is unreachable at the moment, how do you handle it?

Questions that I believe are trying to see how A) can you quickly think on your feet and show that you can handle uncertainty in the work place and B) If you know what the "right" thing to do is?

To be completely honest, I have difficulty answering these, because I'm not sure if its useful or impressive to try and draw on previous experience to help round out my answer or just give it a go and hope they don't look at me like a dumbass. The scenarios sometimes honestly stress me out a little preemptively lol.

Curious to know how you guys handle these questions? I mean particularly in a live interview, the vibe on Hirevue is completely different.