Rafal Grzegorczyk Just try "SELECT table_name, pct_free FROM user_tables;" and my guess is that most will report "10". Ditto for indexes. Creating tables or indexes using "CREATE TABLE ... PCTFREE 0" will not reserve 10% of the blocks for row expansion and will densely pack them instead. Which could mean up to 10% more data per block in places where space is of a premium such as with XE or 23c FREE. Of course, only if you don't actually need to reserve 10% for row expansion. Don't do unless rows are mostly just inserted and not updated. Thanks.

Nice article & great tips. One more that's often overlooked (in all editions) is PCT_FREE. Frequently, keeping 10% of blocks empty is not required. Also a nice performance boost with FTSs, etc.