Tried a different approach to the puzzles today. I decided the easy level puzzles got me 1/3 of the gold normal difficulty, but I could do them much faster than 1/3 the time. So I was just going to do the easy puzzles in my free time. But eventually they started giving me 0 gold. It actually didn't turn out bad, because of 2 of them I got bonus items I was able to sell.