drop table dropme_trg;
create table dropme_trg (d date) pctfree 0;

drop table dropme_src;
create table dropme_src pctfree 0 as select level as a from dual connect by level < 100001;

set serveroutput on
declare
    v_cnt number;
    v_ins_cnt number;
begin
    -- гоняем до 1000 итераций, чтобы хватило точно
    for i in 1..1000 loop
    EXECUTE IMMEDIATE 'truncate table dropme_trg';
    INSERT /*+ APPEND */ INTO dropme_trg (d) 
     SELECT /*+ PARALLEL(4)*/ DISTINCT sysdate FROM  dropme_src;
      v_cnt := sql%rowcount;
    dbms_output.put_line(I || ' : ' || v_cnt);
    commit;
    if v_cnt > 1 THEN
        select count(1) into v_ins_cnt from dropme_trg;
        dbms_output.put_line( 'Inserted rows:' || v_ins_cnt);
        exit;
    end if;
    end loop;
end;
/ 


... 
178 : 1
179 : 1
180 : 1
181 : 2
Inserted rows:2


select * from dropme_trg;

D
--------------------
08.07.2020 15:40:26
08.07.2020 15:40:26