Where I worked we had the Verbal Written Warning (documentation confirming we spoke to you about an issue, but that you didn’t have to sign in acknowledgement), Written Warning (same form, but you signed it and offered your version or someone else signed as a witness that we spoke to you), and Immediate Probation (written warning for behavior that - if repeated in the next year - would get you fired).
We had people who spent years riding the line on written warnings for attendance, and they were always shocked when 1) they slipped up and got fired or 2) discovered that when layoffs came around people on WW were immediately terminated, no severance. Aside from attendance, it was rare (and almost impossible) to write someone up for performance, unless they were mgmt.
We had an incident where a deadline was blown that cost hundreds of thousands of dollars and my boss wanted to put me (VP of the dept.) on Immediate Probation. Investigation discovered that the error was actually by an entry level employee in another dept. with 10 years experience who deliberately ignored procedure because she “figured mgmt. didn’t know what they were talking about” when a memo about a procedure change hit her e-mail. They refused to write her up, much less put her on probation, despite the fact that she conceded both her supervisor and myself had confirmed she got the memo and knew about the change, and she admitted she’d mentioned no concerns to either of us when we talked about it.