This is a most interesting topic and I'm hopeful I can learn something here.
Most of my fishing is done to wary trout in very clear water.
Thus, my tippets have to be rather small. Most times 6X, sometimes, depending on water clarity and fly size,
either 5 or 7X. Most fish average 12 to 14 inches. There's always the possibility of a much larger one. I've caught some of these bad boys and lost a lot more. Usually my fault in fighting the fish but several times I've lost them to various other reasons. Most times it's been at a knot connection, not any fault of the tippet or leader.

Educate me!

Bob