I've heard about US PhD students going on for seven years, ten years, fourteen years, and so on.
In the UK I had to submit before four years. If I didn't do that I literally just failed the degree.
I worked twenty-hour days for about a month at the end and then submitted with one day to go. Not even exaggerating.
Instead, they just get increasingly insistent about you making "forward progress" and increasingly reluctant to keep your funding going.
They may have made an exception.
[It's also possible to "suspend regulations" -- which is University speak for "something happened which the rules don't deal with sensibly" -- and extend a PhD's length, though this is generally accompanied by weeping and gnashing of teeth by administrators. It's much harder to do than it used to be.]
And what’s more four years is the limit - the intention is three.
So in the UK most people go from zero to PhD in six years total, rather than ten or more in the US. And we still manage to get papers into top tier venues in that time so it doesn’t seem to be too short.
I know someone in Austria who got a great PhD in two years with multiple top-tier papers! That’s pretty extreme though.