The Jap loudspeaker unit?

Am I the only one who found this element of the movie dubious, even eye-rolling? The elaborate stage management of the Jap loudspeaker unit, bracketing the Brit refugees every day to coerce them into surrender. Gee, maybe those loudspeaker guys could, you know, FIND the heroes, and KILL them instead of waste time & energy hiking thru the hot jungle climbing trees on loudspeaker patrol. Does anyone know how realistic this was or wasn't in the Pacific theater?