Use of "too"

Hello everbody

I am a bit confused :!: :?

Have you ever noticed that sometimes too comes at the end of a sentence following a comma and sometimes not.(Examples are following)? Is it optional?

1- A lot of time is needed , too.
2- He was killed too.

Why comma in the first and why not in the second?Please help me understand it thoroughly.

Ever yours


Some think it is required and others do not (especially in short statements). To be careful, use the comma in essays and tests.