Years ago I watched two people leave the same company within a month of each other. One spent her last two weeks writing documentation nobody had asked for, walking her replacement through the accounts she managed, flagging a vendor contract that was about to auto-renew on bad terms. The other stopped answering emails the day he gave notice and was, by all accounts, mentally gone a week before he physically left. I did not hire either of them directly, but I heard about both from people who had, and the story stuck with me longer than it should have. It was not really a story about quitting. It was a story about character showing up at the exact moment there was nothing left to gain by showing it.
Most hiring processes are built to observe people when they are trying hardest to be observed. The interview, the case study, the reference call arranged by the candidate themselves. All of it happens under conditions where the person knows they are being watched and has every incentive to perform well. The notice period is the opposite condition. The offer is signed, the new job is secured, and the immediate financial consequence of coasting is close to zero. It is one of the only windows in a professional life where you can see how someone behaves when the audience has, in their mind, already left the room.
What the window actually shows
I do not think this is about loyalty, and I am wary of employers who frame it that way, because loyalty language is often just a way of asking employees to subsidize the company's convenience. What I care about is something narrower and more useful: does this person's standard for their own work depend on whether someone is checking. The person who documents her accounts on the way out is not doing it for the company she is leaving. She is doing it because leaving a mess behind would violate some internal accounting she keeps with herself, one that has nothing to do with performance reviews. That internal accounting is exactly what you want on your team, and it is almost never visible in an interview, because interviews are, by construction, moments when someone is being watched.
At Provieo we spend a lot of time trying to get employers to evaluate demonstrated work instead of self-reported experience, and I think the notice period is an underused instance of the same idea. It is demonstrated work under conditions of low accountability, which is a more honest test than almost anything that happens before an offer is made. I have started asking references a version of this question directly: what did their last month look like. Not their best month, not their most impressive project. Their last one, when the exit was already decided. The answers are more revealing than anything I get from the standard reference script, and people are rarely prepared for the question, which tells you something too.
The mistake I made hiring for speed
I will admit I did not always think this way. Earlier in my career, when I was hiring fast for a growing team, I treated a rocky departure from a previous job as noise rather than signal, because the candidate had a good explanation and the interview had gone well. The explanation was reasonable. What I did not weigh properly was that a coworker of his, someone I trusted, had mentioned in passing that he had checked out entirely once he had one foot out the door. I filed that under normal human behavior and moved on. It was not normal, or rather, it was common but not neutral. Six months in, the same pattern showed up the moment he got a counteroffer he was tempted by. He did not take the other job, but the quality of his work dipped noticeably during the two weeks he was deciding, and it never fully recovered the same intensity afterward. I should have listened harder the first time.
None of this means a rough exit should be disqualifying on its own. People leave jobs for bad reasons that have nothing to do with their character, and some companies make a clean exit deliberately difficult, walking people out the same day or stripping their access before they have a chance to hand anything off properly. Context matters, and I try to ask about it rather than assume. But when someone had the room to leave well and chose not to, that is information, and it is cheaper to gather than almost any other signal in hiring, because it is sitting in the memory of former colleagues who will usually tell you the truth if you ask them the specific question instead of the generic one.
The deeper point is that character is cheapest to observe in the moments that cost the least to fake but the most to fully live out. Anyone can be diligent when diligence is being graded. The last two weeks are ungraded, and that is precisely why they matter.