My experience has been:
1) it helps to oscillate in the queues where there are batch jobs
(otherwise, the most recently introduced batch job gets the CPU at the
expense of earlier jobs that are nearing completion); and
2) it helps to decay in the queue where interactive users are working
(otherwise, somebody doing a CPU intensive task that really, really should
be done in batch will adversely affect other interactive users).
We go a step farther and overlap the C and D queues (so the person doing
that CPU intensive task in the CQ will soon learn that they could get
better throughput by putting their task in the DQ where it belongs).
For example:
------QUANTUM-------
QUEUE BASE LIMIT MIN MAX ACTUAL BOOST TIMESLICE
----- ---- ----- --- --- ------ ----- ---------
CQ 152 232 25 100 25 DECAY 200
DQ 200 234 100 100 100 OSC 200
EQ 236 253 2000 2000 2000 OSC 200