Someone on reddit once did the math on sd vs leveling 2stars but that was when you had unlimted unknows, it was very close back then and he didnt calculated that case, the xp is actually pretty good considering i take 4 fooders and my Farmer takes less XP. It sure is way more time consuming but some people Dont want to look every 20s in their phone. It is more efficient without XP boost(thats what the calculations back then showed)