Overwriting immediately damages and lengthens prose of any kind. Overwriting is the failure to make choices. It's tasteless in the way a lack of control is always tasteless, finally.
Most writers overwrite, especially in a work's early stages.
But that first editing should blow off the chaff. Until sound self-editing cuts the obvious, the repetitious, the gratuitous, the ugly, the contradictory and the unnecessary, the work is still a rough draft. Consider this lead from a newspaper profile of author James Lee Burke. Long beards of Spanish moss are flapping from the cypress and oak trees, convulsing like ominous old men guarding a graveyard. This writer's unwillingness or inability to make choices damages a promising beginning.