Case. The Concise Oxford Dictionary begins its definition of this word: “instance of a thing’s occurring; usual state of affairs.” In these two senses, the word is usually unnecessary.

In many cases, the rooms were poorly ventilated
should be
Many of the rooms were poorly ventilated.

It has rarely been the case that any mistake has been made
should be
Few mistakes have been made.

From: William Strunk, Jr., The Elements of Style, 1918.

As to whether. Whether is sufficient.

Omit needless words.
Vigorous writing is concise. A sentence should contain no unnecessary words, a paragraph no unnecessary sentences, for the same reason that a drawing should have no unnecessary lines and a machine no unnecessary parts. This requires not that the writer make all his sentences short, or that he avoid all detail and treat his subjects only in outline, but that every word tell.

From: William Strunk, Jr., The Elements of Style, 1918.

As good or better than.
Expressions of this type should be corrected by rearranging the sentence.

My opinion is as good or better than his
should become
My opinion is as good as his, or better (if not better).

From: William Strunk, Jr., The Elements of Style, 1918.

All right

Idiomatic in familiar speech as a detached phrase in the sense,
“Agreed,” or “Go ahead.”

In other uses better avoided. Always written as two words.

From: William Strunk, Jr., The Elements of Style, 1918.

For the next month or two, I will be studying and sharing words and expressions commonly misused from: William Strunk, Jr., The Elements of Style, 1918.

“Many of the words and expressions here listed are not so much bad English as bad style, the commonplaces of careless writing. As illustrated under Feature, the proper correction is likely to be not the replacement of one word or set of words by another, but the replacement of vague generality by definite statement.”

From: William Strunk, Jr., The Elements of Style, 1918.