This is an idea that I've seen proposed by mulltiple submods and I personally like, is a twelve turns per year concept. Here's why I like it...
1. The amount of movement that is done on the map per turn, is not nearly enough to cover 3 monthes of a year.
2. The amount of an army that should be able to be mustered in a current (Three Month) turn is not book-like or even movie-like.
3. Alot happened in the LotR series (Which took place in the span of 1 year), and in the game it goes just way too fast and not enough happens.
4. This would allow the game to start of only a few years befor the War of the Ring instead of about 30. Allowing for characters such as Boromir, Faramir, Eomer, and etc... To already be players from the beginning.
These are just my concepts, give me some input
*Disclaimer: This request/idea is meant more or less for Sub-Modders to implement. I don't expect the devs to do it, they're already working on great work ...