Add a weighted backpack and you can massively ramp up the calorie burning aspect of those shorter walks.
"Load carriage" is a thing the military has put some effort into studying. A 50lb pack turns a brisk walk into something that burns 100s of calories. Even an extra 20lbs on your back adds up. It might not feel like a lot, but the difference in heart rate for same perceived effort is shocking.
I have lived on trail, hiking thousands of miles a year with a backpack filled with food, water, and shelter. To hear the claim that hiking with a 50lb pack has the "same perceived effort" is absolutely untrue for me. The difference between 0lb and 20lb is significant. The difference between that and 50lb is monumental. For me, rucking a 50lb pack after about 30 minutes feels like I'm taking hallucinogens, and not in a fun way! Time slows down to a crawl, I can't really understand audio language or even really form thoughts at all. It's like my whole brain stops working and I am nothing but resistance to getting crushed into the ground.
I can ruck a 20lb pack for 20 miles a day for weeks, but even that took a lot of training. Doing that with 50lb feels like it would be impossible. Maybe my 135# body has some limiting factor.
That being said, I love taking out a 50lb pack just to clear my head. It's like forced meditation.
Is a lot and is not a lot at all. When I was using buses to get to work, I got almost 90 min of walking and walking like activities a day just by existing - going to stop, standing on the bus, going to store, walking for lunch or to the office toilettes.
It is kind of nothing if you live "the old school way", that amount of walking just accumulates. If you live "the post covid way" or "car with close parking lot way", then it becomes large block of time you have to carve separately.
6km/h is a brisk walk. You need to concentrate on the walking aspect if you want to maintain that pace.
Slow down a bit to 4-5km/h and you can last much longer, not to mention multitask more effectively (listen to an audiobook, be on a phone call, just brainstorm, etc.) so you don't actually need to set aside hours a day specifically for walking.
Ive started doing 6kmh walk for 30min after gym, two times a week and Ive lost like 10kg in 6 months