I have, on occasion, complained about slack editing in anime and particularly about the half opponent of the week syndrome. However I’m starting to think that anime adapted from light novels has the opposite problem of over editing.
This is mostly speculative as there are very few occasions where I’ve had the chance to read the original material.
One of those was Rocket Girls where the anime covered the first two volumes . The over editing isn’t too bad here, but the 2nd flight in the anime is at least Yukari’s third flight in the novels, and Matsuri’s second. Much of the 2nd flight in the anime depends on Yukari’s confidence and leadership, and the justification for this was much stronger in the novelisations. Matsuri is also much less of a caricature in the novels.
The other was The Twelve Kingdoms where I’ve only read the first novelisation covering the first arc. This is a counter example as the Twelve Kingdoms anime actually took the time to do a proper adaptation that covered all the major points. 
The first time I really noticed this as a problem was with Scrapped Princess. The over editing in Scrapped Princess is mostly in the ending, which needed to be a couple of episodes longer with a monologue or two.
There have also been two painfully obvious examples of over editing this year. The first was Bodacious Space Pirates where squeezing one too many story into the run led to dropping far too many details along the way.
The second, and most egregious, is Sword Art Online which started so well, only to be cut so badly. Several of the early episodes show massive time jumps, and I’ve often seen online commentary to the effect that “X is explained in the books so the anime doesn’t have to! Isn’t it cool!” 
Well, no, it isn’t cool. An anime should not have to rely on viewers having read the novels. An anime should be a standalone version that can be assessed on its own merits, and Sword Art Online has been failing badly in this respect.
It may be that most light novel adaptations aren’t quite so over edited and that I just haven’t seen enough to make a fair assessment. For the ones I’ve seen however, it would have been wise to either cover less of the source material or add more episodes to cover them properly.
If you know of a particularly good example (in either direction) please leave a comment to point it out.