[Justa]

I don't get where this 600,000 year interval comes from. Iirc the one before the last one was 2 million years ago. That'd put the current interval at 1.4 million years.

[Robert A Cook PE]

I understand they are taking the last few "average" intervals:

Roughly: 13 million, 10 million, ..... Keep tracking them closer and closer: 2.1 million, 1.3 million, 0.6 million....

On average, the series indicates the next one "should have" been here several thousand years ago. It's overdue.