Adding variety to poetry books

A poetry book by a single author can contain many types of variety, some more welcome than others.

• Voice/Subject - books that have the variety of a general anthology risk failing to engage readers/reviewers who want to find unifying themes or hope to pigeonhole the poet. Books can be split into sections to give them more "structure".
• Style - Can readers cope with a book that only has villanelles? It's a struggle. What if it's full of free-form poems that all start with a first-person anecdote and end with an insight? That too can be tiresome after a while, though the uniformity is less easily noticed.
• Quality - Most commonly, the best pieces are at the start and the end. To lessen the sag in the middle, a good poem or two can be put in the middle like tent-poles. If there are too many weak poems, readers might wonder why the poet didn't wait another few years, or produce a pamphlet instead of a book. Rather than pad with weak poems, some poets have quirky "high-risk" poems which some readers might love and others hate - a more worthy justification of the book-length.
• Layout - Some poets only write poems whose stanzas are similarly sized rectangles even though the poems aren't metrical. The eye might be bored by this, so some poets add variety - a mix of long and short lines, indentation, right-aligned lines, redaction, extra spaces between words, landscape mode, using no punctuation, using no line-breaks, using "&" instead of "and", using "/" and "//" instead of line-breaks and stanzas, etc.
• Fonts/color - Variation of these features seems unpopular. Text is nearly always black (cheaper if printed, but online there's no need for restraint). There's no variation of font family or size within a poem, or even in a book.