I've just come across a handy little stat in Microsoft Word which shows you the total editing time for your document. In case you're writing in MS Word, this lets you know how long you spend working on your story. The total editing time for my document (the novel I am currently writing) is 18,119 minutes. So I calculated that it's 302 hours of total editing time. That meant I spend 12,6 days working on my novel. That's really not impressive, considering the amount of effort I put into writing that novel.
Interesting - I didn't know this! Just googled and apparently it counts all the minutes the document is open, regardless of whether you're actually working on it. Although my finished MS says 352 minutes... I'm pretty fast, but I think that might be slightly out. ETA: I just looked at the MS I've been beta reading and I've spent 510 minutes on it. I know that one's accurate because this file hasn't been moved between computers, like my own MS. Nobody can say I'm not a thorough beta.