John 14:29 explains that Jesus speaks beforehand to build faith, giving purpose to the statement here.

John 13:19 gives the same reason for Jesus' advance speech: so that when it happens, they believe.

In John 15:11, Jesus uses the same phrase to reveal the purpose of his words: that his joy may be in them and their joy full.

John 16:1-4 shows Jesus spoke these things to prevent them from falling away when persecution comes — another purpose of his while-present teaching.

John 16:12 contrasts by revealing Jesus had more to say but they could not bear it yet — limiting his while-present speaking.

John 17:6-8 reports to the Father that Jesus has given them the words and they have kept them — affirming his while-present teaching.