Stefan
Tyres need to drop more in lap times, as it drops blow 50%/45% . Now cars drive many Laps on ss, but laptimes do not drop fast enough.
There is a noticeable drop in tyre performance after about 40 percent, it's quite clear in races where some people qualify on SS tyres. They pull away for the first few laps, then the soft tyre becomes quicker towards the end of the stint, even though the super soft runners have less fuel.