Exercise of brain or body is its own reward and is worthwhile for its own sake. Exercise of skills one may need one day is also worthwhile.
Having said that, yes, I am often lazy and use GPS routinely. It has led me astray (briefly) on more than one occasion, always because I misused it. It always told me what I was asking of it, but from time to time, I'd inadvertently ask it to do the wrong thing.
So far, I caught errors pretty quicky, because 1) what I learned in years of using a map & compass, 2) knowing that blindly relying on something like a GPS can get you into trouble, so I *always* need to ask, "Does what it is telling me make sense?" When the answer is no, I need to stop, pull out the map & compass, and figure out where the problem lies. 3) by checking the GPS very frequently for "where am I now?", I not only can quickly identify going astray, but I also have a "known good situation" that isn't too far from where I am now.
I am of an age where cognitive decline is a real concern, and wrestle with the convenience of using GPS, and the exercise of reverting to the "old ways" for the mental challenge, and to keep my skills sharp for the day that I may be in true need of them.