Translation of "Fruitless" in Japanese

Let's stop this fruitless argument.

水掛け論はやめよう。

Let's stop this fruitless discussion.

こんな小田原評定はやめよう。

It's fruitless to press him further.

これ以上彼を責め立ててもむだだ。

That is enough. I have had it with fruitless conversation.

もうよろしくてよ。実のない会話にはうんざりですわ。

Attempts to fight the fire with buckets soon proved fruitless.

バケツによる消火活動は、すぐに失敗と分かった。

If a blog doesn't focus an a specific field it is fruitless.

ブログてのはやっぱり分野を絞らんとダメよ。