It’s 95% within minutes. You could probably take an educated guess as to what the 5% will comprise in terms of nationalities that have visa free access to Europe and will not get approval in minutes.

You shouldn’t count on it for last minute trips, but I would suggest that it would be incredibly rare for someone who doesn’t have an established presence/relationship with europe to go last minute. If you do have an established professional or personal relationship that may require a last minute flight booking, pay the 7€ and have an approval on standby for 3 years.

The US requires the same from Europeans via ESTA and Canada requires the same from Europeans via eTA. This is Europe responding in kind to the same burden placed on their citizens.

Th permit process is expected to take on order of hours for most people, and are valid for something like 3 years, unlimited entries.

The US has required the same of Europeans for quite some time now (ESTA waiver).

Edit: looks like they anticipate 95% of cases to be decided in minutes and the rest in not more than 4 days.