Word automatically checks spelling and grammar by default (you can turn this feature off, skip spelling, and grammar check for specific text). It is a good habit to check spelling and grammar after making changes to the document.

When you send a document for review or simply for approval, you need to know all the reviewer's changes. Some reviewers forget or ignore to turn on Tracking Changes. You can compare the original document and the reviewed version to see the differences, but it is more easily block the ability to change the document without Tracking Changes.

Sometimes you need to record new changes in the document that already has tracked changes made under your name. For example, people who have no possibility to make changes by themselves ask you to record their changes. Amendments made by different reviewers have different colors and are easy to find.

Sometimes you need to skip parts of the document during a spell check. E.g., memos and letters can have headings and address blocks with names and other text that slow down the spell checker. Blocks of programming code or foreign words should not be checked for spelling too.
Also you may need to quote words and phrases with mistakes.

There are many professionals who need to know statistics numbers for a page or just some selected block in the Word document, such as the number of characters, words, sentences, etc.

Word automatically counts the number of words in a document while you type. Word also counts pages, paragraphs, lines, and characters. To see these numbers, do one of the following:

Word 365 has an option that allows to use Word document like a board to write some notes anywhere without positioning a cursor. This can help to easily format any kind of document on free style.

Sometimes you need to see a word count statistics without obtaining readability information. For example, you have a limit on how many words a document can be for a particular assignment. Usually, journals, magazines, and newspapers restrict the size of the article.

You can align text between the top and bottom margins of a page if the text on the page does not fill the page. For example, centering text vertically often improves the appearance of short business letters or report cover pages.

When you've created a document and sent it out to your colleagues for editing, you'll probably need to review the tracked changes and decide which to keep and which to jettison.