It’s perfectly okay to break the line with text or graphics, because it adds interest and a sense of dimension.
Even those everyday informational signs can sometimes benefit from a rule. They only take a minute to add.
Sometimes a vertical line comes in handy, creating a panels of sorts, as on Jamahkiri. I don’t always use a bright color for the rule, either. In some cases, a color darker than the background does the job as in the sign at left.
