This example is bad. The composer of Ps 119 may have spontaneously broken out in praise - this we don't know - but what we know of his work, the actual psalm, is carefully and diligently crafted which surely took its time. We could argue that his delight in God's word was strong enough to even fuel such an artistic, sustained and difficult project.
(And he was not conducting a study of systematic theology as Grudem defined it above, either.)
Systematic Theology: An Introduction to Bible Doctrine
it should not surprise us if we often find our hearts spontaneously breaking forth in expressions of praise and delight like those of the psalmist