Limit Excerpt

when the more tag is inserted into a post, WP displays a teaser and inserts a ‘read more’ link. The show entire over-rides this default WP behavior and shows the entire post. The default value is false. Make sure your more tag is inserted where you want the post to break.

The excerpt is shown in its entirety. If you are using excerpts, it assumes you want to show the excerpt.

The shorten text routine was developed to limit the text to a fixed number of characters for specific formatting. The best option for seeing if the shorten text will work the way you want is to play around with it.