Good question. The daily rate was first the best, then the weekly and now the monthly. The rate is probably going to decrease over time as the MNX value show strength. From https://medium.com/minecoin-blog/minexbank-update-algo-upgrade-fb37c7160653

From the beginning of general testing to present, the algorithm works in an autonomous mode with the manual verification of its solutions. Namely, the MinexBank system makes decisions on changing rates by itself, but in fact, they come into force only after confirmation by the analysts of the project.