The maximum number of jobs for each priority, high, medium, and low, can be configured at Database Instance > Job Prioritization, as shown below:

For more information about how to take advantage of this setting, refer to the following Strategy Knowledge Base technical notes:
In this example, notice that the number of connections by priority is set to 2 for all of the priorities. However, when there are multiple jobs concurrently running, the Job Monitor may look like below:

In Strategy Intelligence Server, reports are first resolved by the Resolution Engine before being executed by the Query Engine against the warehouse. While waiting or being resolved, jobs may appear in the Job Monitor under the status of 'Waiting' or 'Executing' and with priorities as low. For this example, 5 jobs have status of "Executing," while it is not all of these executing jobs that represent the query execution.