I very rarely use autoextend. We do lots of batch processing and developers
never put in deletes/archiving until they run out of space. It's also a nice
stop to a "runaway process" Or I might autoextend to a limit. Having said
that, the ones I do autoextend on base on the extent size of the tablespace
when using uniform extent sizes. For autoallocated extent sizes I use 64Mb
as it used to be the largest extent size created with autoallocate though I
haven't checked with 10g.