There's a fourteen-day review window for all pull requests before they count toward completing the challenge. Once a participant has submitted four eligible pull requests (ready-to-review, not drafts), the review window begins. This period gives maintainers time to identify and label spammy pull requests as invalid. If the pull requests are not marked as invalid within that window, they will allow the user to complete the Hacktoberfest challenge. If any of the pull requests are labeled as invalid, the user will return to the pending state until they have four eligible pull requests, at which point the review period will start again.