Similar to government bills trying to get passed into law, the larger the document the more it obfuscates what is contained. Making it more difficult to make a correct judgement based only on documents provided to the court. This leaves it more in the hands of the lawyers to present their client's side of things (sometimes creatively bending the truth) versus objective dissection of the actual facts. It also leaves it more in the hands of paid expert witnesses who interpret key sections of the overwhelming document in favor of that side as they're likely to be directed to interpret key sections of the document by the lawyers of of the side presenting the documents.
On the flip side, you want to cover all your bases with as many words as possible. You'd want to attempt to cover anything the opposing side might try to bring to light, no matter how minor. If you need to go to an appeal, you can then always point out a key section which perhaps didn't come up in the original court proceedings. Etc.
But the key, often times (especially if your claim is questionable), is to make it as dense and obtuse as possible in order to make it such that the document requires expert testimony that you provide to put things in as favorable a light as possible for you.
Regards,
SB