cvsup server operation

[Vladimir V Egorin]

After a long downtime, we've brought cvsup15.freebsd.org back
to life.   I've noticed however something odd in the logs.
We run updates (update.sh script) once per hour, however there
are some clients that request updates periodically every 5-10
minutes, sometimes as often as every 2-3 minutes.   This doesn't
make any sense to me; this potentially could result in denial
of updates to other clients if the queue is full of regular
guests.
I'd be interested in hearing whether other cvsup sites implement
any access control mechanism that denies update to clients
that have requested it very recently in the past, or shall I just
pay no attention and let it be.
Many thanks,
-- 
Vladimir