I don’t want to say that the Royal Wulff is the only fly you need to catch brook trout on mountain streams in the eastern United States. It’s not. Some say other flies work better in certain situations and on certain streams. There are those who claim terrestrials are the only way in mid-summer. When hatches occur many insist matching the hatch is a must. When waters are raging nymphing could be your best bet. And so on. No doubt these are all valid views at various times.