Are most mild interjections treated as parenthetical elements and set off from the rest of sentence with a comma or commas?

Yes, most mild interjections are treated as parenthetical elements and set off with a comma or commas. Here's why:

* Interjections are words or phrases that express strong emotion, surprise, or a sudden feeling.

* Parenthetical elements are phrases or clauses that add extra information or commentary to a sentence but aren't essential to the main idea.

Examples:

* "Well, I guess we'll just have to wait and see."

* "Oh, no, I forgot my keys!"

* "Wow, that's a beautiful sunset."

Exceptions:

* Strong interjections are often followed by an exclamation mark (!) and are not set off by commas. For example, "Wow! That's amazing!"

* Interjections that are part of the main clause are not set off by commas. For example, "Goodness gracious, what a mess!"

In general, if an interjection can be removed from a sentence without changing its meaning, it's likely a parenthetical element and should be set off by commas.