Why must Tor continuously contact directory servers?

[hikki@xxxxxxxxxxxxx]

When I supervise Tor's traffic, I see that it very often contacts nodes 
which are directory servers. It's not like +/-2000 nodes change their 
statuses that fast.

I wish there was a way to reduce this to like 1 time each day or even less, 
because it adds a lot of unnecessary traffic, at least in my opinion, trough 
my own line and the whole Tor network.
***********************************************************************
To unsubscribe, send an e-mail to majordomo@xxxxxxxxxxxxxx with
unsubscribe or-talk    in the body. http://archives.seul.org/or/talk/