The good news is, those shoes look very typical of a proper working brake system in my opinion. They've been heated pretty good a time or 2 though. The fact you mention they look the same all the way around is good, no cracks so they even though they got hot a time or 2, it wasn't to drastic. They obviously never got a drum off inspection with all that brake dust allowed to accumulate. If those were bonded shoes I'd say they're 60% worn. Because they're Riveted shoes, I'd say they're 75%-80% worn. Yes, they're good enough to be put off for a few weeks if need be.
Rather than try to race or rush and do all 4 brakes at one time. I'd take your time and concentrate on 1 axle at a time. Do the rears, and do a thorough job. As cheap as brake parts are on 1/2 tons, don't even consider rebuilding the wheel cylinders. The cost difference is next to nothing for NEW wheel cylinders. Use Brake Clean and get all the nastiness off the backing plate. Use brake clean on the new shoes to make sure you clean off any grease from handling and installing the shoes. Have the drums turned. Make sure the adjusters are nice and clean and that the threads are clean and the adjuster moves freely. Lube the adjuster threads with White Lithium grease to keep them moving freely even if they get wet in the future. Lube those pivot points that Jerry is pointing out. Inspect your hardware for damage replace as needed or just replace the whole kit. If do them right, you shouldn't have any rear brake problems for several years. Because it so easy, it's never a bad idea to pull the drums off for an inspection when you rotate your tires or every other time you rotate your tires. When you do, spray brake clean and get all the brake dust residue cleaned off before reinstalling the drum. That will avoid all those black streaks you see in your current shoes. That's just brake dust getting smeared and imbedded into the shoe because it was allowed to build up. Brakes last many years, IF THEY ARE MAINTAINED. Of course towing and aggressive stop and go city driving means check them more often. Just like anything vehicle related, more abuse means maintenance more often. Like Trans Fluid and Filter change, normal driving 50,000 miles is fine, if you're towing a boat or toy hauler, then you change it at 30,000 or even sooner depending on the abuse you put it through. NO different with your brakes. Then of course, Disks don't require as much maintenance and quickly inspected and looked at every time you rotate your tires. So take your time, do the rears 1 weekend, then you can do the fronts , 2, 3 or 4 weekends later. Doing them correct and thorough is more important than getting all 4 wheels done at the same time. JMO