The other thing that strikes me is that we don't know the details of the contract between the MSC and the client. My guess is that it has multiple layers with multiple financial benchmarks for the MSC. In other words, it likely has details along these lines:
* Every store will be shopped at least XX times per quarter in order for the MSC to make the contract.
* No store will be shopped more than XX times per quarter.
* Stores can be shopped more than the minimum number of times (up to the max) for an additional $XX per visit.
* XX% of stores will be shopped each week.
* XX% of stores will be shopped each month.
*At least XX% of visits will occur during each of the meal periods (breakfast, lunch, dinner, late night).
* Etc.
Such a variety of factors will lead to different pricing at different stores (and in different regions) from week-to-week. The MSC has all this data and almost certainly a computerized algorithm that dictates how much compensation should be offered so as to maximize their profits, based on their progress in fulfilling their contract with the client and reaching various desired benchmarks... As a result, sometimes, a store will be available to be shopped several days in a row. Other times, it will be off-the-board after a single shop. A couple of people doing routes of them twice a week could significantly depress the compensation offered in a specific region. A bunch of people routing with them could depress the market nationwide. Etc. These factors, combined with the MSC's adjustment of pricing so as to entice shoppers into doing them could easily create a pattern of changing payment amounts that make it very difficult for shoppers to truly plan around and take advantage of.
Yesterday, some of the shops around me got to $20, a little higher than what folks in other areas are reporting. Today, those same shops are down to $14 - which is higher than where they started last week.
Hard work builds character and homework is good for your soul.