I once worked in a cafe in my teens, we would be paid up until half an hour after close to do cleaning. Mopping the floor was the last task I did, it would usually end up running 5 or 10 minutes over the time I got paid. Your post makes me imagine dropping the mop half way through finishing the floors and walking backwards out the door while flipping off my boss because that half hour ticked over.
"The moment I step through my work door I set a timer for 7.5 hours." This is a terrible work ethic. You set a timer? I don't agree with doing unpaid overtime either, you certainly won't see me in the office on a Saturday, but sometimes things need to be completed before you leave for the day. But maybe that's just my opinion working in a remote office in a vastly different time zone to head office where my work needs to be delivered.
Although not a metric, I did chuckle that you state your co-workers work twice as long as you (14hrs vs 7.5) yet have three times as many fixes as you and then reference the reason for this is the time they spend at work.