The Alarm is built into the machine; it is a prayer that runs in the background which is tied into body responses. This makes sure no damage can be caused to you, however when killing critters the damage comes the next day in the form of plugged liver\kidneys and elimination organs. Certainly I would not have wanted to tackle some of those days without Beck's and other tools, and I sure couldn’t have gone to work.
Top 5 Worms means a 1 minute zap for each of these worms. A nine minute zap on an entire tray can take 20+ minutes to complete and frequencies are piggy backed onto frequencies during this time, could be 60 minutes worth of zapping in that.
This is certainly not a built in function of the unit, it is entirely manual/operator controlled and I wouldn't depend on the alarm for this...