Answer. This is a great question, and one that doesn'tget asked enough. The applicable statute is ORS 90.630 (Termination by landlord; causes; notice; cure; repeated nonpayment of rent.) In summary, the statute provides that a landlord may terminate a rental agreement that is a month-to-month or fixed term tenancy by giving to the resident not less than 30 days' notice in writing before the date designated in the notice for termination. There are several types of violations listed, but the one addressing your question is subsection (1)(a): '_a material noncompliance with ORS 90.740... ."
ORS 90.740 (3)(j) requires that the resident "behave, and require persons on the premises with the consent of the tenant to behave, in a manner that does not disturb the peaceful enjoyment of the premises by neighbors."
The text of ORS 90.630 that directly addresses your question is found at subsection (4):
"The tenant may avoid termination of the tenancy by correcting the violation within the 30-day period ... ." (Emphasis added.)
So clearly, when it comes to conduct, if the bad behavior continues during the 30-day period, the 30-day notice is violated the moment it re-occurs "within the 30-day period". Thus, if after receiving the 30-day notice, the resident repeats what he was told not to do, you do not have to permit the bad behavior to continue for 29 more days - you may file immediately. To take a more serious example, suppose the tenant was speeding through the community, endangering the other residents. Certainly, if that continues during the 30-day period, it has not been "cured" and you may file the F.E.D.
However, out of an abundance of caution (at least when the violation does not endanger the health, safety and welfare of the other residents) you might consider allowing the repeat violations to re-occur a couple of times, just to make sure you've got clear evidence of an intentional disregard for the 30-day notice.
Also, note that ORS 90.630(3) requires that the 30-day notice state '_facts sufficient to notify the tenant of the reasons for termination of the tenancy and state that the tenant may avoid termination by correcting the violation... ." This requires that you be very clear, both in explaining in the notice the nature of the violation, and exactly what steps must occur to avoid termination.
I suspect the confusion about whether a landlord must wait the full thirty days before filing for eviction arises because when the violation does not involve conduct, but relates, say, to a static violation, such as a failure to maintain the space, the full thirty days must be observed. That is, the resident has the full 30-day period to cure, e.g. cleaning the yard, or removing dilapidated furniture from the street view.
To put it another way, when the conduct requires that the resident "stop" doing something, the affirmative act of doing it within the 30-day period is, per se' a violation of ORS 90.630(4); but when the 30-day notice requires that he "commence and complete" a certain activity, it must be done within the entire 30-day period. If it is not completed within the 30-days, only then may the eviction be filed.