Every tracked page is checked once a week, on the day you choose in Settings. A page you add is checked within a few minutes rather than waiting for that day.
Why we do not sell faster checking
How often we check is what decides how much traffic we send to other people's sites. If we charged for checking more often, we'd end up hammering the sites we rely on and getting blocked, and that would hit every shop using us rather than just the one that paid. So everyone is weekly, and we spread shops across the days of the week.
When a site refuses us
Some sites block anything that isn't a browser, and often only some of the time. When that happens we note it, wait several hours, and try again on the next run instead of pushing harder. Coverage usually fills in over a few weeks. The Competitors page shows how many checks are succeeding for each site.
When a site asks us not to crawl
We follow robots.txt. If a competitor blocks us there, their prices won't appear at all, and we'll tell you that's why rather than leaving you wondering.