I've had a full beard since I was 16, myself, which was... 7 years ago now? When I say full I mean full, too, no scraggly teen growth here. I still shave my neck and cheeks daily, since it /still/ doesn't grow like it should on the cheeks, and anything less than Duck Dynasty lengths on the neck is a major no-go, but still, that's like half as much shaving as I'd be doing if it was everything. I also take a pair of scissors and a comb to it about once a month to thin it out, and keep it clean like I do my hair, but beyond that it's fairly low maintenance. I've never really had that issue with it getting itchy, if anything that's more of a problem for me on the rare occasion when I shave it off totally.
I also had long hair at 16. I miss my long hair. I'll probably grow it out over the Summer a year after I get hired in a permanent teaching position. There's too much chance of running into a principal who's an ex-cop or soldier (or just an old fogey who still associates long hair on men with hippies, in a negative manner) to do it while I'm still trying to get full employment.