Why did David and Jonathan need the arrow signal?

Question

Just before David left Saul's service for the last time, he and Jonathan arraigned a way to communicate with one another in code:

Jonathan, out of his love for David, adjured him again, for he loved him as himself. Jonathan said to him, “Tomorrow will be the new moon; and you will be missed when your seat remains vacant. So the day after tomorrow, go down all the way to the place where you hid the other time, and stay close to the Ezel stone. Now I will shoot three arrows to one side of it, as though I were shooting at a mark, and I will order the boy to go and find the arrows. If I call to the boy, ‘Hey! the arrows are on this side of you,’ be reassured and come, for you are safe and there is no danger—as the Lord lives! But if, instead, I call to the lad, ‘Hey! the arrows are beyond you,’ then leave, for the Lord has sent you away. As for the promise we made to each other, may the Lord be [witness] between you and me forever.”—1^st Samuel 20:17-23 (NJPS)

But after they execute their plan, they end up meeting with one another directly:

The boy suspected nothing; only Jonathan and David knew the arrangement.—Jonathan handed the gear to his boy and told him, “Take these back to the town.” When the boy got there, David emerged from his concealment at the Negeb. He flung himself face down on the ground and bowed low three times. They kissed each other and wept together; David wept the longer.

Jonathan said to David, “Go in peace! For we two have sworn to each other in the name of the Lord: ‘May the Lord be [witness] between you and me, and between your offspring and mine, forever!’”—1^st Samuel 20:39-42 (NJPS)

If David and Jonathan are able to meet even when Saul is in a rage against both of them for friendship, what was the purpose of setting up the arrow signal?

Answer 1

I think this question must be broken down in two:

1. Why did Jonathan and David make up this plan?
2. Why did the author of the book include this detail in the narrative?

The first question has never really bothered me, thus this answer is not the result of extensive study, nor have I consulted any commentaries. I have always envisioned that they made the plan not knowing how safe the rendezvous would be, if there would be anyone present that might tell Saul, etc. But then it simply turned out that the arrows would not be needed. David saw that Jonathan was alone and simply walked up to him.

As for the second question I think this story reinforces the greater narrative about Saul's animosity towards David being evil and caused by wrong motives. Jonathan is the contrast and him and David being really affectionate friends also shows how David is not an usurper or driven by malice towards Saul and his family.

The plot with the arrows emphasize the danger and the care Jonathan takes to help David. The actual meeting emphasize the affection and purity of their hearts.