I’ve had times when I regularly walked 6 miles at sunrise and 6 miles at sunset so a 15 mile walk doesn’t intimidate me in fact I see the time on Google Maps and know I could do it in at least an hour less. That 15 miles is a product of Los Angeles just being a freaking huge city, not because it's particularly wasteful of space but because there are 12.6 million people in the metro area.
Comfortable = continuous sidewalks, lots of palm trees, no places where the road goes up into a flyover without a shoulder never mind sidewalk. I doubt you could go 5 miles in Atlanta without encountering one of those. (Which is NOT an accident)
Now I am not recommending that particular walk for walkers in the bottom 95% but I’d say that much of the city is like that and walking 1-2 miles is usually easy —- note the walk of fame is one of the great walking destinations anywhere. Sure LA drivers run red lights like Jack Bauer in 24 but Atlanta drivers will kill you on the sidewalk.
To be fair I have spent time in places like Hollywood, Santa Monica, and Beverley Hills, it might not be so good in the “bad” parts of town.