I also fall into the fill it and smoke it camp. Of course, you have to be a little careful with the first few bowls to ensure you're burning tobacco, not wood, and smoke gently to the bottom. Any method that doesn't harm the pipe works just as well, but in my experience, smoking full bowls is more pleasant, even in the beginning, than smoking half-bowls, and it seems to be we should do everything we can to increase our enjoyment of the pipe from the starting blocks.
There are a couple of things at play, here. In the dark ages of the pipe, I don't think the briar was as carefully cured, at least amongst the common pipes (I'm not talking about the fancy names, here, but the pipes smoked by the average person in our grandfathers' days), and the break-in process was probably a little more painful. We don't have to worry so much about it, now. Most pipe companies do what they can to ensure decent smoking from the first bowl. (When 40% of the adult male population smoked pipes and factories were turning out millions of pipes per year to satisfy huge demands, the notion of aging briar for a few years would have been fiscally impractical.) We're perhaps more fortunate in this regard, today.
Then, there's the difference between "breaking in" and "seasoning" a pipe. The first few bowls are important to begin building a protective barrier layer between tobacco and briar, but once that's accomplished, the equally, if not more important process of seasoning the pipe begins. As the briar takes up the oils of the tobaccos we smoke, its flavor begins to deepen, and the pipe delivers a richer, more engaging smoke. Only many bowls over a period of time will accomplish this.
My advice has always been not to perseverate too long over methoology, and just smoke carefully, enjoying every bowl as much as possible. Only over time will a good pipe become a great one. It's always worked for me.