We update our NYT list enrichments every Wednesday. Please note that not all NYT lists are updated on their end at this time. In fact, some of NYT lists have an update cadence of every quarter. The "Last Modified" date you see published with your list is the last publish date that NYT claims the list was updated. We've observed that the NYT API is ahead of the web site in terms of best seller information, so if you see a Last Modified date that is before the date of the list on the NYT web site, that is because we get our updates directly from the API.