Blocking websites with usage limits is technically possible only in the Safari browser. You can do this in a similar way to blocking apps:
Go to Schedules > Blocklist > Save.
Select Usage limits and set the daily usage limit for the chosen websites.
Under Apps and Safari websites, open the Other category to see a list of recently viewed websites in Safari.
If the website you want to block isn't listed, visit the site in Safari, then return to AppBlock. The website should now appear in the Other category.
Please note that usage limits will only apply when you access these websites via the Safari browser, as iOS cannot track website usage in other browsers.