I only use a spreadsheet for the "big picture" and not my daily word counts.
For the daily word counts, I have a sheet of note paper. Pocket-sized, though I almost never carry a pad in my pocket, but I make them that size for consistency and in case I do, and there are cases for when I do, just not for word counts. Anyway, the top of the sheet has the starting word count, which is typically the word count from the end of the previous month. Then, each day, I write the new total word count and next to it is where I write the words written for that day. Occasionally, I resort to using a calculator, but I try to do the math in my head. I figure it's a good idea to give the brain exercise and not rely on machines all the time.
For the "big picture" I have a spreadsheet listing all my books and planned books. I update periodically with how many words are completed per book. I don't have a set period for when I update. I updated once in 2016, once in 2017, three times last year and five times so far this year. Usually, I just update when I finish something or think of another WIP to add.
For example, when looking through the notes I had from my Newton from the last backup (two days before the note I wanted to be sure to keep - oy), I found a note for my writing. Evidently, I had planned to write a screenplay for a short story I had written five years earlier. Never did write said screenplay and not sure there'd be a point in doing so now, but that was the plan back then. Also, I had planned to finish writing two novels that, twenty-five years later, remain unfinished. LOL. The other one was to write a novel with a title I don't recognize, so obviously it's something I've forgotten. Do I add that to my WIPs? Well, if I could remember what it was supposed to be about, I would.
But, that's typically when I update, when something is finished, when I have a new idea for a book or when I find a note for an idea I had a long time ago. Then each work has an estimated word count for completion. More like a target amount.
And then I'll update my current average word count. I think the last time I took the average of several months, maybe the year so far, not sure, but I then use that to calculate how many years it will take me to finish everything on the list. I really, really need to get back up to a minimum of 1,000 words a day average. Otherwise, it will take me 72 years to finish everything. At 1,000 words a day (minimum), I can wrap them up in about 13 years.