I personally feel that whether a dog can be free fed has a lot more to do with individuals than breed traits. You'll see lots of people claiming poodles are picky eaters, but mine would definitely be pumpkin-shaped if I allowed him free access to food! In my own experience food motivation isn't a puppy thing - the dogs I know who don't have great appetites were like that from the day they came home, and the chow hounds were always that way. Obviously some medical conditions and medications can affect appetite, but in general food loving puppies aren't likely to slow down. At least not before adulthood and slowing metabolism catch up to them and their waistline. Even if she doesn't seem to be packing on the pounds right now, keep an eye on her poop. Frequent, softer stools are often a sign that a dog is taking in more than they can use.
There are other benefits to feeding on a schedule. It's easier to notice changes in appetite and eating behavior, especially with multiple dogs, with each getting fed individual potions, and this can be really important in catching health problems early. It's easier to provide a specialized diet or supplements to just one dog if they wind up needing it. I always have a decent idea of how hungry my dogs are likely to be, and can plan their training sessions to take advantage of that (eg not so hungry they try to take my hand off, but hungry enough that they stay keen and motivated in distracting or challenging environments). Hungry dogs are also way easier to convince to accept a pill. And just the reduced likelihood of attracting pests. If I left kibble out that the dogs didn't finish (hypothetically, my boys are bottomless pits), the ants around here sure would. But you'd probably notice if you had that problem with free-feeding your older dog, haha.
