Creating a BIGFILE tablespace -- "optimal" NEXT size?

For BIGFILE tablespaces -- does "one (NEXT) size fit all"?

create bigfile tablespace big_ext

   datafile '+data'

  size 1g autoextend on next 4g maxsize 32t

  extent management local autoallocate;

 

Let's say that the tablespace already has 24 TB allocated, therefore it has extended over 5000 times. For another tablespace, I do this:

create bigfile tablespace big_ext2

  datafile '+data'

  size 16g autoextend on next 32g maxsize 32t

  extent management local autoallocate;

Once the space is allocated for the tablespace in the disk group, is there any additional overhead when allocating new segments in the tablespace? Or accessing existing segments? Thanks.