I have the opposite experience. When people typically stick around for the majority of their career, there's no incentive to capture knowledge thoroughly. Onboarding time was noticeably longer because of it.
The ideal is almost certainly somewhere in the middle.
The people who have only been on the job a couple months are probably not truly onboarded themselves, hard for them to document what they don’t know.
The people who have only been on the job a couple months are probably not truly onboarded themselves, hard for them to document what they don’t know.