[ns] Is it necessary to remove the unused packet headers?

[galaxy-huang]

hi, everyone,
    In chapter 12 of THE NS MANUAL, the author wrote that "By default, ns includes ALL packet headers of ALL protocols in EVERY packet in your simulation. This is a LOT of overhead ..."
    But i find that many ns tutorials, experiments never mentioned this problem. my question is, Is it necessary to remove the unnecessary headers when we are doing simulations, especially when need to calculate delays and throughputs? Is the BIG unnecessary headers affect the packet transmit time(when calculate the timeout of the event, are the length of all headers taken into account )?
    Thank you in advance!