The total incubation target time is 504 hours. There is nothing wrong with adding a few hours but do so carefully and make it part of your hatchery programme in order to not negatively impact broiler performance. If we set up programmes to pull at 506 hours (that is when the pull should occur) - don't pull at 512 hours. If variation occurs then we are holding chicks longer than the profile calls for and something is wrong with incubation.