question about tables and datafile?

question about  tables and datafile?

 our customer have a question,

example, we have two table his0901 and his0902 (090* means table create date，each table about 1million row, ) in tablespace gw, in tablespace gw ,we have 24 datafile within the gw.

when we check dba_extents which datafile his0901 or hist0902 belong to， we find a thing ,

that  his0901  is allocated  in of all 24 datafile, and his0902 is also allocated  in of all 24 datafile.

i have a question , what is  table  allocate by datafile mechanism ?

in my opinion, when insert data in table, oracle will  random allocate a datafile to the table, and then all newly insert data to table will in