Extents: Less or More?

I'm confused about managing the number of extents for an object. The rule of thumb I've always believed that the fewer the number of extents (preferrably one) an object has the better. But recently, while taking the DBA course at an Oracle Education center, I was lead to believe that the number of extents for an object doesn't really matter.

I can see the logic for this as most I/O is random and blocks are read and written, not extents. I've even heard that having too few extents can be a problem for Parallel Query. Is this true? The only real benefit I can see in having fewer extents is that there are more contiguous blocks which would benefit I/O for full table scans.

I could spend a great deal of time resizing segments to keep their number down, but I could certainly spend the time on other tasks and still squeeze in that 60-hour week. Any suggestions?

Thanks,
Brian

Ps. Running Oracle 7.3.2 (DEC OpenVMS) and Oracle 8.0.3 (Windows NT) Received on Sun Feb 01 1998 - 00:00:00 CST