Breville BES870 single and double shot question
I have recently purchased the BES870 and am relatively pleased with it however still trying to get the extraction process down to pat and as a result i am still adjusting the grind, grind amount and tamp. However my question is with the single and double shot feature. I noticed a lot of people are using the double shot, is this simply because they prefer their coffee double shot or its much easier to get the extraction correct? Also I have found the Breville machines dont allow a larger cup\mug to be placed under the porter filter. Why is this so? its quite annoying as the only work around is to poor espresso shot into a smaller cup and transfer to a larger cup.