I'm having trouble parsing this question or understanding why it was tagged across so many topics.
But the short answer is that with any complex paragraph formatting, there is a point at which one format will not do everything that is desired (such as outdent every third line, or alternately indent lines, or stagger the indent on each paragraph line).
If the poetry (or similar material) is very irregular, a series of styles will have to be used to get the desired effect on each line or set of lines, and it may be most efficient to use some selective overrides (such as tabs) to "go the last mile" without dozens of defined styles.
For more regular formatting that still exceeds what's considered normal for prose and business text, multiple styles may still be needed in each verse or stanza. For example, a stanza that has the first line outdented 2em, a second line at "normal" indent, a third line that is outdented 1em, and then a fourth line at "normal" can only be done with two styles, one for the first two lines and one for the second. (Let's not get into scripting wizardry here...) By adjusting the top, bottom and line spacing, successive stanzas with this format, but separated by extra space, could be easily formatted and tweaked.
Hope that points you in the right direction.
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