I've been doing most of my walking off track lately. I've got a bunch of paper maps with points of interest, mainly waterfalls, and by using the contour lines etc I just drop a pin on the Avenza map where it matches and off I go no dramas so far.
Today I was looking for something but I only had the coordinates 38°35'19.4"S 143°44'60.0"E. So, I just found that spot in Avenza, dropped a pin and set off. I didn't check it too thoroughly because it looked right on the face of it. When I got there I obviously wasn't in the right spot. I checked it against the coordinates (the page where i got them has a google map plugin) only to find I was 650m off. 650m is not a trivial distance where I was and I had to chuck it in.
Anyway, clearly I was kidding myself I knew what was going on.