I noticed our ground speed was lower than normal landing a 737 in LAS one day. It was the old 200 model so just cranked the speed up a bit. It was way before GPS. It worked but when we lost 20 knots at low altitude it would have been nice to have GPS GS to verify eyeball GS. Never had autothrottle in those days however. Eye ball GS indication works if you can see the ground.