Designers should always make sure not to repeatedly use the same/similar mechanics in a game. In some games the addition of redundant abilities/mechanics can make the controls overly complicated and awkward. This can be most often noticed in mmorpg environments where when expansions are released, new abilities are often added but rarely removed. To keep gameplay fresh and compelling designers should always consider avoiding/removing redundancy.
Example[]
World of Warcraft pruning abilities
World of Warcraft has been running for 12 years. Over this period many classes have had abilities added, changed and removed, along with their entire play style changed multiple times. For example in the expansion Warlords of Draenor, many classes and specs had abilities pruned from their spell books because they no longer fit in the style Blizzard envisioned for the spec. They also did this again in the most recent expansion Legion to simplify game play while fitting into their new vision of the classes and specs.
