If you withdraw 100 euros from the ATM and do not specify another denomination, it will usually be one 50, one 20, two 10s and two 5s – the "housewife mix." Municipalities proceed similarly when designating building areas: building areas are divided into sections intended for certain types of houses. For row houses, plot sizes that would not "work" for detached single-family homes are sufficient. In land readjustment procedures, the previously pooled plot sizes are intended to be recovered according to the new division. The size classes are often arranged in blocks. Where the municipality itself was the owner and freshly parceled, it is done similarly – as described at the beginning, based on the expected demand.
Die Traufhöhe zielt eventuell auf drittes Geschoss mit Dachterrasse ab?
That may well be / would be an explanation. Mainly, however, it was probably about a uniform ridge height maximum. Whether every builder can fully utilize this is less important.