In the late game, when I have 5-7 raxes I often need to book 15-20 marines (lings, etc) at a time. To do so right now I'm pressing 'a' button 15-20 times... which take me solid 5-10 seconds....

Is there any way to do that quicker? I believe I can configure my Windows to do 'auto-repeat' with SMALL delay, but I will need to do that before starting playing starcraft and change settings back once I left.

Is there any better way?