A well-built, healthy young vlcak should be fed well (i.e. given quality food) but look (too!) thin. Only then at the age of 2-3 will he/she reach the optimal weight and looks. It's also vital for good HD/ED results not to overload the joints. Regular 'rib test' to check if the pup is developing well seems a good idea.
Though I agree that it's sometimes hard to listen to all those comments about walking a poor, underfed pup, shackal, fox, etc. etc.
PS. I doubled your post Ina, sorry