• The abused users will make the required work in the last day of the campaign or will finish all the jobs in 1 day.
• If the above happens, the advertisement of the campaign or the traffic is low.
• It would be hard for the manager to put stakes in the participants (Except if he/she will put the stakes at the end of the campaign)
This is just according to my perspective, but if you're a manager you should conduct a weekly report because it shows that the campaign is organize. So far I haven't seen any campaigns that didn't require the participants to make weekly reports. I think it's one of the standard rules in the bounty "Make a weekly report". I think you're referring to social media campaign right?
Wow, you help me easy to understand why we have to make weekly report. The purpose of the bounty task is adverting, the advertisement's result with high traffic will help the project go successfully. Many thanks.