truncate utility (not split)

[csj <csj@mindgate.net>]

Is there a utility to truncate files such that a single smaller piece or
no more than two pieces are produced? Something like:

(1) original_file -> small_chunk (bigger_2nd_chunk discarded)
(2) original_file -> (smaller_1st_chunk discarded) big_chunk
(3) original_file -> small_chunk + big_chunk

split would be suboptimal, especially in scenarios (2) and (3)::

original_file -> small_chunk_1 + small_chunk_2 + small_chunk_n
delete small_chunk_2 small_chunk_2
concatenate small_chunk_*

Hope you understand what I means. TIA