Someone had discovered that StarCraft II mining AI has a problem, the worker will just sit there a while after mined the mineral before returning to cargo (the base). Somehow you can bypass the mining AI by queuing up mining (shift right click on mineral) and return to cargo command (shift + c) repeatedly until the queue is full. Refill the queues when needed. It allows you to gain 7% more mineral than automated mining by using the AI.
Cheers! Now you're not so free during the opening. This might actually become standard opener :)
来源/Source: Early Game +7% Mineral Boost via Dan & Nick at GSL TG-Intel Starcraft II Season