Group training is not out of the question, but as Devil's Advocate the modern world (and the US in particular) has a huge shortage in skilled trademen, and one of the big contributing factors is that many of these skills require the sort of guided on-the-job training that is simply impractical to provide in a school setting. And Internships are basically short-term Apprenticeships. The Teacher/Apprentice model is far from outdated even in modern society, and can still win out against group/classroom training in several important ways, many of which I think apply to Magical study as much or more than others. For that matter, Id submit that the vast majority of actual education in the modern world is still ON-The-Job Training.
That being said, I have to assume that there is typically more shared teaching and classroom settings than we've seen Harry involved with, but he skipped all the normal apprenticeship stages (since he was inducted as a full member based on his fight with Justin) and went straight to probationary member. I think it was Cold Case that mentioned how much of the standard education he skipped.
I will say that I think the group teaching Wizard Academy mindset works far better with the Wardens than it necessarily would with your average Member, were the practices can be far more specific/specialized and would not necessarily be required to have skills outside your own wheelhouse. But somebody has to teach all Wardens the Sword, or how to run an Investigation, or any number of specific Duty-required skills that a non-warden Master simply wouldnt be expected to know let alone teach.
I think the question boils down to how Standard those early lessons really are, versus how much individual problem-solving and adapting lessons to Talents, especially at the early stages when magic does weird shit like making an apprentice literally glow when they get a compliment. Either
A)the early lessons just establish the basics, later lessons (1-on-1 or classroom) could be taught by increasingly specialized instructors with decreased class sizes until it becomes basically an apprenticeship; that's more or less the modern system with single classes at low levels, with increasingly specialized classes in high school, college, and beyond. Or,
B)The early education NEEDS to be closer to one-on-one while Control is established somebody knowledgeable and dedicated to supervise and troubleshoot and customize lessons to individual emotio0nal blocks, etc. Then only once their magical skills and control (and understanding) have reached a certain point would they have enough common ground with other practitioners to take advantage of group teaching methods.
Or Neither is overwhelmingly the case, and so for the most part either method could work, and it's just a matter of relative resources.