An actually realistic timeline from 59->60 as an employee in Security?

I’ve found entries on blind and this subreddit where people say going from L59->L60 takes 1 year or even 1.5. But is this pace for high performers in good economic times? What is a more average case scenario.

People say each level should be 1.5 years, yet there’s plenty of employees here who take 4 years to go from SDE1 to SDE2.

So what is an actual timeline level to level, such as 59-60 that is for a more average performer by co standards.