How to set up Priorities?

We have three types of priorities: low, medium or high

Let’s assume that we have only low priorities in routing - in this case threads are assigned to teams and then to users in chronological order.
If we set both low and high priorities in routing then threads from projects with low priority are assigned in chronological order; threads from projects with high priority create second queue which is emptied in the first place (threads in second queue are also assigned in chronological order within the queue; threads from "low" queue are waiting until the "high" queue is empty).

Example / routing table:

We have a thread which fits (based on keywords) project 1 and project 3 it will be assigned to Team A (because project 1 assigned to Team A is higher in routing tab.)

We have a thread which fits only project 2 it will be assigned to Team B and it will go to "low" queue.

We have a thread which fits only project 3 it will be assigned to Team B BUT it will be in "high" queue (if there are threads waiting in "low" queue, this thread will be assigned to a user earlier).