Not only does the musculoskeletal system have to recover and repair, but the endocrine system and the central nervous system must repair themselves as well.
If you train too intensely, your body will stay in a catabolic state and you won’t be able to sufficiently reach supercompensation.
However, if you aren’t training with enough intensity (minimal weight) or you aren’t training frequently enough, you will no longer stimulate your body to produce further gains.

There is a fine line between greatness and failure.