Some fine novels have been short (think The War of the Worlds, by HG Wells; or Heart of Darkness, by Joseph Conrad). It depends on the story. The Lord of the Rings isn't a lesser novel for being c.600,000+ words long - its size is required in order to describe a whole fictional world (although, reading it, I can't help but wonder whether a little trim here and there might improve it).
As for 'that', I know many people who use the word often in speech, and just as many who don't. There are other overused words: 'said', 'the', 'man', 'woman', etc.; and many overused phrases: 'beautiful woman' (the heroine in thrillers is always a beautfiul woman) comes to mind.
There are also overused ideals. A few heroes who don't value democracy might be refreshing . . . but I now moving very much off topic.