Many ITM sites want to disable default ITM situations so that unnecessary alerts are not sent to the operations. In old days, we usually disable the situations by running a simple script. One such example of the script is posted below.
http://blog.gulfsoft.com/2008/03/disable-all-default-situations.html
This task is much easier with ITM 6.2.2. While seeding application support, ITM asks you to whether you want to add the default managed system groups to the situation distribution. If you answer no, the default situations will not be distributed to any managed system unless you explicitly assign them! However, this feature is applicable only for fresh installation of ITM 6.2.2 and may not apply to those who are upgrading from old version of ITM.