Study groups

Why is it recommended to study scriptures in groups or with a teacher/ learned person?

Many reasons and explanations

1. Collective effort, sum of all
2. Sharing understanding & experiences
3. Reading individually one may take it 
1. Literally & not understand the subtle knowledge
2. Each one will understand as per his/nature & circumstances 

Whether its Gita study groups or Bible study groups, the objective & endeavour is same : knowledge for spiritual growth!