I think we've all figured out by now that spending 8 hours per day 'at work' doesn't necessarily mean 8 hours of productive output.
After time tracking with Harvest for a while, I've figured out that I max out at 90 minutes or so of really good concentrated creative output - in my case, writing. It seems crazy low, but I just feel mentally tired and prone to distraction if I stretch it much longer than that. The rest of the day often falls into lower-effort marketing and admin tasks.
Am I just kinda lazy, or is this common? I'd like to step up my game but I'm not sure how.