Oracle Database Discussions

Hi,

I am reading below link :
http://download.oracle.com/docs/cd/E11882_01/server.112/e10595/tspaces002.htm#ADMIN10065

And it has one sentence "Automatic segment space management delivers better space utilization than manual segment space management."

My question is : Then in which cases Manual segment space management is good choice in compare to auto. If Automatic segment space management delivers better space utilization, then why oracle has also introduced Manual segment space management? I mean, what special advantages can be obtained with only manual segment space management, which are not available in automatic segment space management.

Any example will also help me to understand it please.

Thanks,