Today has failed the rebuild of an index with ORA-01652 error. The point is to rebuild an index is more expensive in space that delete and recreate it. A reconstruction maintains the old index while creating the new. If we have an index that holds 20 gigabytes and rebuild, we will have in time given two indexes of 20 gigabytes each. If you delete and rebuild have only 20 gigabytes, of course, you need between 1.5 and 2.5 of size the index temporarily while it is rebuilding.
HTH – Antonio NAVARRO