Occasionally I've wished the circuits had yellow zones like Le Mans. But the trouble is, like previously said here, is that if medical car is needed, all track action must come to halt.
Also if the accident happens in the first turn, drivers crossing the finish line are approaching the turn with such velocity, that sector 3 has to be yellow zone as well, thus no one would be able to improve their time. And let's remember that in qualifying, red flag saves precious time in the clock for further attempts. Any delay would only possibly mean that there's not enough time for hot laps (if the accident happens with 2 minutes remaining in the clock).
And frankly, it's unfair that drivers who are past the accident could finish their lap, but those that are approaching the crash site have their lap ruined. So what's lucky for some is unlucky for others. In race conditions, yellow zones are also unfair, because if there's like a 10 second gap between the drivers, and the one in front has to slow down, but then yellow zone is lifted just before the driver behind crosses it, it means the gap is decreased by multiple seconds - because of luck.
And lastly, they probably wouldn't recover car under yellow zones but would use SC anyway, or red flag the session in case of practice or qualifying.
Edited by Ruusperi, 09 April 2022 - 09:15.