>>23346103Typically an LN adaption would do 3 to 4 volumes, Knights & Magic did 5 because they had to get Ikaruga in for merchandising reasons (which only panned out years later anyways) and it first appears in volume 4, and if you don't want to just cliffhanger in the middle of a story arc you then have to go to 5.
I would say as much as anything it compresses battles though. Like in the LN Kerhilt escapes the fort with 3 Tellestarles and the back weapons on the second are destroyed by the Knight Gears while they are doing hit and run attacks in the dark, in the anime they make it 2 Tellestarles and a Kaldatoah so they can skip over that to an abbreviated cartoonier version of the conclusion with the wire anchor. In general there's more explanation for things because you can get away with more exposition in that medium but the overall structure isn't fundamentally different.