A rigid adherence, for example, to the rule that not more than two consecutive lines should end with divided words will not justify a badly spaced, unsightly line.

There are many things that look worse than a hyphen at the end of the last full line in a paragraph.
Avoidance of dividing the last word on a page, however, would justify even bad spacing, because of the gain to the reader.

In the last resort, the interests of the reader must always have first consideration.
Division is greatly affected by the length of the measure.

A long measure, 18 or 20 ems or more, gives greater opportunity for arranging the spacing, but, on the other hand, makes division on short syllables conspicuous and out of proportion.

Very short register, as in two-column Bibles or in cases where illustrations are inserted in the text, presents very great difficulties and often calls for division which would not be allowable elsewhere.