An interruption during the checklist is not a pause — it is a reset
Pilots treat interruptions as pauses. They handle the interruption and resume the checklist from where they believe they stopped. But memory for checklist position is unreliable, especially under the time pressure of an active taxiway or a cleared-for-takeoff instruction. The only reliable response to an interruption is to go back to the beginning of the section that was interrupted. The cost of re-reading five items is seconds. The cost of missing one item is the flight.