I was once told my theology professor to stop including so many “thats” in my papers. I complied, and remain critically aware of using unnecessary “thats” to this day. But there is a place for using “that.” Indeed, sometimes it is right to write multiple, consecutive “thats” in a single sentence.
For example, “I know that that professor does not like me using the word ‘that.’” But if it’s right to write “that” twice, could it be right to write “that” that much more? Yes. That “that that” is perfectly acceptable English should be obvious to all. But that’s not all the “thats” that that professor should allow. That that “that that” that I spoke of earlier is proper, no one can deny. But could someone deny that it’s possible to use six “that thats” in a single sentence? They could, but that would be a mistake because now that that “that that” that that professor did not like proved to be an acceptable use of English, there’s no telling how many more “thats” can be used in a sentence. Perhaps we could use as many as seven. But I would understand why, upon hearing that, that that “that that” that that professor initially objected to would no longer seem all that objectionable. And that is all I have to say about that.