Learning by maps is better, but there are things a GPS with do better. Maps can be outdated. So if there are new streets a GPS is more likely to find it for you while the map your using stays outdated. Also when delivering a misload or delivering in the dark with poor street visibility a GPS will come in handy. In this case typing in an address is faster then pulling out a map to pin point where your at and where you need to go is a lot slower. And then you'll have to be thinking where to have to turn, head straight, etc, before you even get there.
I dont think Saturday Ground is possible without GPS unless you already know the whole center by heart. It's too cluster
trying to determine how to run it when everything is spread out in miles.