Management makes threats about in-office reporting every few months or so but the spreadsheet doesn't track time, only days in office. If you've put in 6 hours, 4 hours, 2 hours and haven't been talked to, you're fine. In my experience employees only get in trouble not because of the report that's generated, but because of bitter coworkers reporting to their manager.
I've been doing full hours but I'd love to change that if this is true? Is there any way to confirm this?