Each month of vesting you can absolutely move shares out of GOOG (minor restrictions on insider trading, but regardless of your level you can set up automated strategies), and most employees probably should given the correlated risk between Google taking a nosedive and employees losing their jobs.
The vesting is unrelated. With no promotions or raises the 4yr bump is uninteresting. With those, they match your TC, but they happen _during_ those interesting career events. They describe some subset of your compensation for the next 4yrs. You can still invest them however you choose. You can still leave at any time (unless you believe that in your personal case the promotion train is better than the job-hopping train). You could have just as easily job-hopped and invested the surplus in GOOG.