If you are running services and P6 on the same server, you should keep the defaults. If you have apply actuals work that needs to be done immediately, you should set the Interval low (e.g., 10s) and the Concurrent Threads high (e.g., 20). Remember that if the server is actively applying actuals, all users will experience delays in the application.
To set your apply actuals settings:
Open the P6 Administrator application.
In the Configurations tab, expand your configuration.
Expand Services/Apply Actuals.
In the Interval field, enter the amount of time to wait before running the next available job (in 1d1h1m1s format - specifying only numbers without letters implies milliseconds).
The default is 10s.
Enter anything from 1s-24d20h31m23s647.
In the Concurrent Threads field, enter the number of processes used for this service on this server. A value of 0 indicates that that this job will not run on this server.
The default is 2.
Enter anything from 0-20.
In the Active Mode field, choose true if you want jobs processed continuously until all jobs finish. Choose false if you want each job processed according to the Interval.