As already mentioned, a lot depends on where you work. In some divisions of my department, you should know your way around fairly well after a few weeks. In others, it is common for officers to use GPS or maps because the division is so large.
Even if you work a larger area or division you will come to know the problem areas quickly, as SoCoDeputy said. So, even if you don't know all of the streets, you will most likely know the "hot spots" soon enough.
I used to care. Now I take a pill for that.