There are two main types....valley frestoners and high altitude mountain gradient freestoners. The first is usually a series of tributaries culminating into giant freestone rivers -the Catskill and Montana rivers can describe these waters. In teh summer there is strong trout migrations towards ice cold thermal brooks and refuge areas- Horton Brook on the Beaverkill is one example.
The later has very cold mountain spring caverns that keep its predominantly wild trout-mainly brookies, happy and cold all day.
The mornings usually see the tiny trico hatches couple with a few rusty Pseudocloeon spinners (bwo). Also a few very large leviathans are stirring from the night feeding foraging binge before they go P/D for an afternoon snooze.
Afternoons are the S/R mind game venues that trout play with terrestrials; ants, beetles, hoppers..etc. I say' mind games' because though they really relish these morsels, they somewhat always question the authenticity of their being...and make very complex/compound rises
Night and evening activity brings out the A/A behavior of the larger brown trout that go on the hunt for anything that moves: large pteronarcys stoneflies, mice, snakes...anything that will feed these 70 million year old modern dinosaurs...concentrate around bridge pools, and deep pools with wooded structure.
Next...spring creeks !