Actually , those kinds of boo-boos happen more often with templates , or so it seems to me. Bits wandering , clamps sliding , mis-aligned , BACKWARDS ! I've heard a lot of tales with templates. Of course , the trade-off with free-hand is the templates ability to reproduce the same guitar repeatedly , and get clean precise cuts. To a degree at least. I could churn out 'splorers and strats/teles all day by hand and make em all look good enough when compared side by side with a proper one. The thing that holds me back right now is my own building and finishing skills , which I'll only improve if I practice. One guitar at a time , I suppose.
Try it out on a headstock shape once. Draw it out and jigsaw it. rasp and sand to taste. Its fun. I just compared my HS up there ^^ with an overlay of a real hockey stick and for a "look once , draw and cut" its really close to accurate. I have enough meat to trim in one spot to make it exact , but I overcut the bottom curve by a bit already. After tidying , it'll be a bit smaller than stock , but I'm still happy with it.