If we're measuring the duration of effect of hormones, shouldn't we measure the duration of whatever it signals/triggers the action of or release of, rather tha

If we're measuring the duration of effect of hormones, shouldn't we measure the duration of whatever it signals/triggers the action of or release of, rather than the molecule/peptide itself? If whatever it signals has a shorter half-life, then yeah, the duration of effect is going to depend on the hormone's half life, but not if whatever it signals has a longer half-life of effect.