Running a sequence item in sequence and sequencer

In reply to dave_59:

Is there any motivation why should one prefer doing following:
start_item(pkt);
assert(pkt.randomize());
finish_item(pkt);

instead of:
assert(pkt.randomize());
start_item(pkt);
finish_item(pkt);

I see no critical disadvantage in following later. Kindly correct me if I am wrong.