Many landlording books and courses recommend posting the 3-day notice-to-quit immediately when the rent is due. It's probably 10-20% asserting/protecting the landlord's rights under the law and 80-90% "training the tenants to hold up their end of the contract as they signed it."
Wouldn't it be more normal to post a "pay or quit" notice? The significance of this is the landlord is legally obligated to drop eviction proceedings if you pay within 3 days. I don't think jumping straight to an unconditional notice to quit is normal or even legal in many states. Indeed, many states require repeated violations before a landlord is allowed to post an unconditional notice: https://www.nolo.com/legal-encyclopedia/state-laws-unconditi...
I happen to be in Texas where any degree of nonpayment of rent, no matter how minor, innocent, or unintentional, can be used to justify an unconditional notice. But a "pay or quit" notice would have still been a less aggressive option available to them that would have achieved the same goal unless they had some ulterior motive (e.g., decide whether to proceed based on my skin color when I walked into the office with the cashier's check).
It is commonly understood in property management that you absolutely cannot appear to give breaks on paying the rent late, otherwise your tenants will prioritize making their car payment, cell phone payment, credit card payment, etc before paying rent. Obviously, if you have a long term renter who has always shown responsibility in the past, property managers will make exceptions.
