OK, so I'll reword the question: why is the watchdog limited to 45 seconds, rather than being left on?
ANother question, which is relevant to GRJ's scenario, is how long must the power to a channel be off before turning it on will re-trigger a watchdog?
GRJ: I would not that your solution does not account for the wifi, which, unless the app is left on from the last session, has to read the layout each time a loco is newly-started.