Why a cell would not have to make a lot enzymes

Cells have to make enzymes. For the ones they don't make, you must consume food with said enzymes

Second messenger systems: The amino acid-derived hormones epinephrine and norepinephrine bind to beta-adrenergic receptors on the plasma membrane of cells. Hormone binding to receptor activates a G protein, which in turn activates adenylyl cyclase, converting ATP to cAMP.