LP - Honest question – why not issue a simple speed reduction, save time on the radio and tweeking about in the cockpit, power for TAS to ground speed/ distance calculation etc. Always wanted to know as it is one of my 'pet' though unspoken, very minor dislikes; especially on short-ish sectors or at short notice, or, on descent, through the lumps. It's doable, and no sweat but – I've always wanted to ask....?