There's rarely ever just one approach to an endeavor. I think Helen's advice to a student is well designed to make him/er aware of both a) the things to be considered and b) ways to look at those things. After going through the exercise a time or two, a student should begin to develop a "feel" for the process and become gradually less dependant on the formulaic approach.

When you think of lyrics as poetry, you will usually find an inherent rhythm in the phrasing, which translates to tempo. I'm no expert on poetic technique, but most seem to have what I think of as a syllabic formula - a mathematical pattern in the number of syllables in each unit of the poem. Those patterns are often irregular in the sense that the number of syllables may vary. When converting such poetry to song, that irregularity can be resolved by either changing time value of notes so as to accommodate all the syllables, or by adding "extra" notes to be played where there are no syllables to be sung. It sounds more complicated than it really is when you try to reduce it to words, but, it is a way to begin.

Another wat to encourage students, ultimately toward the same end, might be to have them start by writing parodies to songs they know or like. That would make them see the rhythms of words quickly. It would also force them to expand their vocabulary.