Great questions, not sure we have a way to measuring impact/success.  We give tests and can see the results of lesson and plans.  SEL growth is harder to quantify, so making it impossible to value or track progress.

SEL is the process in which students develop the ability to understand and manage themself.  Mainly their emotions as they grow.  They also need to learn how to build healthy relationships, make responsible decisions, and navigate social situations effectively.  Which many do not do. 

One of the best ways I feel I get my student thinking is working in groups whether in a classroom or at home this naturally brings out social-emotional skills.

List of things is:

1.People have to communicate clearly

2. Listen to different perspectives

3. Figure out how to handle disagreements when they come up.

It also pushes individuals to be accountable to the team and work toward a shared goal, which helps build empathy and stronger relationships over time. Conflict resolution is not just winning the majority vote.