为啥可以rs.stepDown(5)?

node024213(mongod-4.0.8)[PRIMARY:27017] test> rs.stepDown(5)

{

  "operationTime": Timestamp(1559285765, 1),

  "ok": 0,

  "errmsg": "stepdown period must be longer than secondaryCatchUpPeriodSecs",

  "code": 2,

  "codeName": "BadValue",

  "$clusterTime": {

    "clusterTime": Timestamp(1559285765, 1),

    "signature": {

      "hash": BinData(0, "+wx8ofa+0+/Mqxvh4GKzhpERdTA="),

      "keyId": NumberLong("6680315174974390274")

    }

  }

}

我这里执行报错,stepdown period must be longer than secondaryCatchUpPeriodSecs

我看了secondaryCatchUpPeriodSecs默认是10啊? 为什么写5可以?