For such a programme the Parallel Mode gain on mapping efficiency is not a great benefit. This is particularly true under the assumption that the survey area of deep extragalactic mapping programmes is considerable smaller than for galactic surveys. Moreover, these observations will cover a range of depths where both PACS and SPIRE sensitivities are demanding. As with the galactic surveys, it is possible that PACS could be operated in parallel to provide additional data but in considerable lower sensitivities.