Dcades ago, I learned to strike-in to create clear drone tones but no chanter. Recently, I have observed - and have heard - the strategy has changed. Strike-in seems more gentle, allowing some double-tone of the drones until they "pop" or "lock" in at a pressure which is still slightly less than required to sound the first E.
At least one Glenfiddich championship soloist allowed a howl or whistle for a good time, then showed a controlled lock-in of the drones, followed by the chanter and a quick fine-tuning before proceeding to his tune.
What is the preferred sound today? Is it the same for solo and more regimented band strike-ins (i.e. - does a band NEED to have all clear drones at the fifth beat, or is the double-tone or whistle now allowed/preferred)?