Was it shortened because they needed as many soldiers as possible or did they stick to the normal amount of time used before the war started?
I have written extensively several times before about the training experience of U.S. troops during the war here, here, here, here, here, and here, but I'll summarize the most informative parts below using several tangentially-related comments taken from those threads, which also contain more information in and of themselves. Other advantageous posts to read are here and here.