Rewards for contest and speedy projects will increase when time passes by and the project hasn't been fulfilled. The objective of this behavior is to incentive more Pros to participate as well as to allow more Pros, with higher rates, to be invited.
As Pros improve their stats, the reward offered to them will increase as well. We reward a Pro's experience and good performance! The more our clients choose a Pro as the winner of contests, the more reliable they become. This will result in more invitations to projects and higher rewards.
While simple projects may be accepted by Pros quickly, complex projects, or projects that have very specific requests, may be harder to complete.
For more information on this topic head to the community thread.