Believe me RSIT is less "Bullshitty" and much more kit focused than it used to be. At least it is now relevant and thanks for that can go down to the Maj who turned it around about 5 years ago. At 21 in the mid 80's my 4 relays in the troop were all picked up on RSIUT because the "LED" on the heater under the safe were US in all 4 dets. On closer inspecton, the LEDs turned out to be plastic stops to prevent the rotary heater switch spinning. That was when RSIT was stupid and irrelevant.
IIRC, the book said it had to be 1" high. The jobsworths translated this to EXACTLY 25.4mm - and got arrsey because nobody makes stencils that size. I mean, god forbid you used a 24mm or a 25mm stencil - where was that extra 0.4mm?