Our local guys have been instructed not to sound the whistle to end a period, unless something "weird" happens to end the period (foul right before horn, shot not released before horn sounds, horn doesn't sound with all zeros, etc.)
I don't believe that there is anything in the NFHS Rulebook that states that an official shall sound his whistle at the end of a period. I don't believe that there's anything in the IAABO Mechanics Manual that that states that an official shall sound his whistle at the end of a period. I don't have access to a NFHS Mechanics Manual, but I would like to know what it states. A little help please ...