Still doesn't really address the reality that onboarding is dreadful at most startups, I think. Docs tend to be bad/outdated/nonexistent and even "grab an onboarding buddy and talk through it with them" can fail easily, especially if the business is growing quickly. I do think there should be a cliff (maybe six months for seniors/9-12 months mids/juniors) where as the manager, you take a really hard look at how the person has adapted to the job/what they're contributing, while also taking into account their and the company's situations.

Yes, after feedback is given I expect them to fix the behavior or to show progress in 2-4 weeks, if not then deliver the notice, or in some companies formalize a Performance Improvement Process.

The way I give feedback is by investigating first what is going on inside their lives, sometimes things happen and they just need some time to recover.

If there are no problems in their personal lifes then I give clear examples of where they are falling short, how that impacts the team, and what needs to be changed, and then give them incentives, like how fixing this behavior can improve their career.

Generally, feedback given to early hires is due to lack of communication, most new hires that we onboarded had tendencies of disappearing, skipping meetings, and not replying for many hours.

Turns out they had a freelancing background, where doing those things is common since they talk with clients once a week.

So I walk through them to set up their tools, set up notifications, configure a proper calendar, and general teamwork advice, not to just rush through delivering tasks and then they start to ramp up.