Well, keep in mind the recovery is less the total calories burned and more the act of putting your entire body weight on the soles of your feet for eight hours on cement floors in crappy shoes.
Also, four to five hours of walking is not "pretty light exercise". It's a decent workout. Average speed for walking is around 3mph not 2, and if pressed by electronic monitoring and management, a bit faster than that. Probably one of the best forms of exercise out there, but rarely done for most people don't have the time. Low intensity workouts over long periods of time have a different recovery than high intensity workouts over a short time. The direct calorie comparisons don't really do it justice...
As someone who works at a relatively large warehouse for a billion pound UK retailer, i can attest to the "walking is not pretty light exercise". Sure, if you walked for leisure, it'd be nothing, but when you have such high targets you need to reach and management always peering around corners and always ending their conversations with "Okay now, hurry up you're falling behind", it makes the experience way more difficult. Also, the breaks are set out in a way that makes life absolute hell (for me, anyway). On Saturday, we have 10-15 minutes after 2 hours. Then 2 hours after that, we have a 45 minute unpaid lunch. Then 2 hours after that, we have a 20 minute break. That day goes by so fast and without any problems. On Sundays, we have a 15 minute break less than an hour after our shift starts. After 2 hours, we have 45 minute unpaid lunch. 2 hours after that, we have our last break. Then we have a solid block of 3.5 hours without any rest. It typically takes me a full day of resting my feet to feel better because i'm not the lightest person, and being on my feet for so long especially without rest really makes a big big difference when comparing Sat and Sun.
Yes, i have made it known to senior management that this break arrangement is bizarre for Sundays (it's because we work 12pm - 8pm on Sat but on Sunday, it's 2pm - 10pm so everything shifted forward 2 hours apart from the breaks, which have to accommodate to permanent staff who still work 12pm - 8pm on Sunday). They just tell em they're working on it. Not a lot of people listen to agency workers there, seeing as though we hardly last 2 or 3 months, but i've been working for almost a year now and still i've not got half the attention that's given to permanents. Has it got to do with unions or something?
Also, four to five hours of walking is not "pretty light exercise". It's a decent workout. Average speed for walking is around 3mph not 2, and if pressed by electronic monitoring and management, a bit faster than that. Probably one of the best forms of exercise out there, but rarely done for most people don't have the time. Low intensity workouts over long periods of time have a different recovery than high intensity workouts over a short time. The direct calorie comparisons don't really do it justice...