Pine Creek, Lower Muddy Creek, Lackawaxen R and many many more are great examples of what pcray is explaining.
I remember catching quiet a few large wild browns that were in trickle tribs of Pine Creek that you know.....didnt come from that stream. Of course it was summer time.
I'll admit that I am an occasional trophy hunter. I go looking for and even stalking the same big fish. In the past, Ive done it for weeks at a time. I've even got a large map with years of fish movement data for the Lack. I think I have a fairly good handle how they move in that stream. That was not an easy project.
However, when I do this kind of fishing its more about the hunt than catching the fish. I want to observe and analyze. It can be amazing the rituals just one fish will do over the course of years.
One such example that sticks out in my mind is a (at the time) 7 year old brown from Lititz Run. Most large fish in that stream hold to only a few holes most their lives. Not this fish. In the winter she would be in the middle reaches of the Conservancy, oddly enough during the summer she would migrate miles downstream to just below the C&R area. Only to once again return in the winter. Its odd because it is the opposite of what you would think. Lititz Run warms considerably in the C&R area as opposed to the Conservancy. There are only 3 factors I can think that made her do this.
1) In the conservancy there are more scuds and cress bugs than the C&R area. Thus more forage over the winter. Also the occasional feeding from TU.
2) In the summer there are more Caddis and midges in the C&R area than the Conservancy. That means more pupa/larva along with Cress Bugs and Scuds.
3) The C&R area got a heavier feeding than the Conservancy. Both farmers and TU would feed the fish. During the winter, these feedings were less because its cold out ;-) Who wants to go feed big old stockers when its 5 degrees out.
While this example is an artificial environment, it really was a fun puzzle to think about and it helped me become more interested in fish behaviors. Clearly this fish had a pattern or ritual and I think her "IQ" was a bit higher than the other big fish. Especially since she would always be just down stream of the C&R area. One could assume she just liked that area. I think she never saw much pressure down there. Not many people venture out of the "reg area". I have not seen her in years. She probably died of old age.
Either way, do some research and pick a likely spot. Fish it a few times. Just walk it a few times and try to see what you can spook. We have more big browns utilizing marginal water during certain times of the year than most people think. When they are in those waters they are difficult to catch. More forage and often large bodies of water. The time to catch them.....................is when they are on the move.
The point is, if you define a "trophy" as a fish that significantly outsizes it's peers, that situation most often happens when the fish may have spent some of its life in bigger, richer waters where perhaps its less of a "trophy", and then migrated to the smaller waters where it's a monster.
I consider a trophy a fish that made me earn it. One I had to come back for. Maybe one that made me solve its riddle. One that took that impossible cast (under the branch in the riffle, to drift a fly into a undercut before the large rock snags me from 30 yards away with tall grass behind me and all with a broken rod ;-) ). It could be a fish that made me read, study and understand all the variables I could of its particular ecosystem. It could be that 20" Wild Brown I helped that kid catch in Wyomissing years back. Your 1st Letort Brown. That wild brown I caught on a BWO on Adams secret spring creek in a hurricane ill never forget. Could be my daughters first trout on a flyrod. There are so many ways a fish can be a trophy. Most people think size........for me in the end.....is it something ill remember all my life?