Could anyone give me some explaination how it works?
job_queue_interval in init.ora and interval in a job

I am setting up a snapshot refresh group with interval 10 second and set job_queue_interval=20 in init.ora. It seems refresh time about 10 seconds. if job queue wake up every 20 seconds how it possible do refresh less than 20 seconds?
when I reverse it, job_queue_interval=10 and job interval=20,
it seems still refresh in 10 seconds.

currecntly I manually check the result to get timing, does any view can help me to figure out the "true" refresh time?

thanks in advance