For players that are looking at using scrolls of wisdom to complete grain consumption sourses that were added to the Acadamy.... note that light troops tend to have a zero grain consumption without the use of grain consumption courses so developing these is pointless.

More to the point, advanced accounts that have their stables and farms max level tend to have a grain consumption of 0.01 grain per hour.   Developing max level (level 40) agreements for horse units will not have ANY effect on the grain consumption of horse units, so do not kill time or scrolls developing this skill.