With the general consensus being that the current qualifying system is (one of the) best we've had and could have, there always remains talk and debates about 1-lap qualifying.
And the one thing I don't like about the current system is a qualifying lap generally is not that critical: drivers most often either have a banker lap to fall back on (with a slightly worse end result but not the worst) or they can have another go. And that is the thing 1-lap qualifying offers: they have to make that one lap count, showing who can perform under that ultimate qualifying pressure to nail that one lap. However, 1-lap qualifying has the negative element of changing and different track and/or weather conditions for each driver.
For like a year or so I have the following idea in my head, which is simply a single (rule) change to the current qualifying format, and I really would like to see F1 give it a try:
The format stays exactly as it is now, but - like at the Indy500 - when a driver goes for a qualifying lap he loses the lap(time) he'd already set.
You think you can do better? Show it. But there's no fall back on your previous attempt anymore. You have to deliver the lap when you go for it.
So like I say: putting the pressure back on the qualifying laps.
Of course it requires some rules and regulations to establish when a driver is considered to have started a Q-lap, to avoid the arguing that it was just a fast in-lap, second build-up lap, or whatever. Which can be kept quite simple, like for example if the first 3 seconds of the lap have been driven at full throttle, or the first couple of mini-sectors are faster than x seconds. Or they could go for an engine setting that has to be used on in-/out-/warm-up laps which limits the max. engine power and if that setting is not used they are considered to be on a qualifying lap. Or like with the pitlane speed limited there's a setting with a limiter for in-/out-/warm-up laps limiting the maximum speed to for example something like 30km/h less than wat is normally achieved on a Q-lap (more than fast enough to prep your Q-lap, to not be a driving road block, but a big enough difference to lose valuable laptime for a Q-lap.)
Anyway, that is something that can be solved and regulated.
Same as that when you have to abort your lap due to a yellow or red flag or impeding, your previous lap will be reinstated .....or not, as you decided to take the risk.