this is kind of bothering me. how closely is progress related to muscle growth? it seems not very close in my experience.

ex.

my chest is my weakest part and also progresses very slowly, maybe 1 rep a week. but, recently its been growing very fast even though progress is still very slow.

my back is my least developed part. my back strength goes up very quick, 10lbs a week on deads, BB rows, and 2 reps on pull ups. but doesn't seem to grow much.

biceps never progress anymore, but they grow.

triceps progress every workout, but are very slow to grow.

i just find this kind of odd...any explainations?