Google Alternating Serps?

[jimbo_mac]

I have noticed a cycle within my targeted keyword category.
One particular site seems to get updated every 3-4 days and shoots to the top 5.
Below the category description in google -

Category:XXXX/xxxxx/etc
www.sitename.com - 10k - 4 Jul 2002

A few days later the site drops a few positions down the list. It appears again after 3-4 days with new date.

Any help appreciated.

[przero]

I have seen similar things as well. This month the cycle seems to be 3-4 days. Last month they were alternating every day. Anyone know what's going on?

[hurlimann]

No but I have seen it happening for 6 months plus on some keywords we track.

When the cycle starts it tends to be predictable.
What causes it, when it starts and for how long is less predictable.