The standard was to move people with terrible O2 sats at the start of the outbreak to ventilation immedatley, even if they did not seem to bad.

That seems to be replaced with providing high levels of O2/CPAP and only moving people to ventilation when that is not sufficient, even if O2 sats would normally indicate ventilation. This is why vent usage is a lot lower this second time round, even with more patients in hopsital.

I would be surprised if they put someone on a ventilator just because his O2 level was low without first putting him on O2 and maxing out the flow. Little experience that I do have is that people are first put on O2, then if their saturation remains low they increase the flow until they can increase no more. At that moment they are a candidate for a ventilator.

Maybe they "relaxed" the criteria after a while if ventilators showed bad outcomes but when people are maxed out on O2, there is little you can do.

[1] https://elemental.medium.com/how-one-covid-19-doctor-became-...