Jesus didn’t just sit around the synagogue all day. Jesus didn’t just hang around the temple courtyard all the time. Instead Jesus went out where the people were. He didn’t isolate himself alone on a mountain top. Although he certainly did retreat there from time to time for prayer and refreshment. No. Jesus got out among the common people.
As I see it he probably did this partly from necessity and partly from practicality. Jesus did go to the synagogues to teach those who were gathered there, but the self-righteous people who controlled the synagogues didn’t like his message and so they kept throwing him out. Jesus found it necessary to teach on the hillsides and lakeshores because the traditional avenues were closed to him.
This reminds me a lot of the ministry of John Wesley. John Wesley was in many ways a traditional churchman, but the powers that be in the Church of England in his day didn’t appreciate his radical message of repentance from sin and faith in Christ alone for salvation. As a result he was thrown out of church after church after church until at last he had no places left he could go to preach.
John Wesley didn’t allow that to stop him. Being shut out of the churches he turned to the streets and pastures and began to preach there. And in those places crowds numbering in the multiplied thousands gathered to hear him proclaim the gospel. Far more people heard John Wesley’s sermons in the highways and byways than would have ever heard him if he had been confined to the sanctuaries of England.
Not only did far larger crowds hear him, but also far different crowds heard him than if he were to preach only in the churches. He would go to the mines and mills and preach to the workers as they were coming and going from their shifts. People who never would have darkened the door of the church flocked to hear him in these unusual locations.
And that leads me to the practical side of why Jesus went out to the lakeside to preach and teach. There he could preach to far more people than would ever be able to crowd into a local synagogue. And there he would find an audience to teach that he would never be able to reach in the temple courts simply because they never went there.