The amount of planning done is incredible. The Hobbit vs LOTR is a perfect example of what years of planning can do for the quality. To film 4 films at once is incredibly ambitious.
LOTR was a complete mess of a production. Tons of re-shoots.
http://ew.com/article/2014/05/17/viggo-mortensen-lord-of-the-rings-interview/
Mortensen, who portrayed Aragorn in the trilogy, says Jackson and producers were in a lot of trouble before the first film proved to be a massive hit with both critics and moviegoers. Officially, [Jackson] could say that he was finished in December 2000 hed shot all three films in the trilogy but really the second and third ones were a mess, Mortensen says. It was very sloppy it just wasnt done at all. It needed massive reshoots, which we did, year after year. But he would have never been given the extra money to do those if the first one hadnt been a huge success. The second and third ones would have been straight to video.