Prayer walk are not scriptural.

We might not share the same opinions on this, but let me tell you why I say that, for purpose of comprehension.
1.
Whenever we pray in the name of the Lord Jesus, God ears us.

2.
You also need to know, that there a different kind of prayer, each prayer for a definite purpose. You can read "HOW TO PRAY EFFECTIVELY" BY THE MAN OF GOD PASTOR CHRIS. to understand the rules for prayer.

3. When it comes to the prayer you do to cause a change, that's the prayer of intercession, also called supplications.
Here the set, changes. You can't do it in the streets.

4. For sure you can speak in tongues and edify yourself while walking in the streets, but you can never cause a change in the streets.
Look at the example of the Apostles, when Peter was kept in prison.
They were praying in their houses. Acts 12:13

The point is this, the prayer of intercession is the one required to cause a change, and for it to be effective, you need to stay:
*Indoor, or in a lonely place: Act 12:13,
Also take the example of Elijah: 1Kings 18:42

You can also pray alone look at Daniel 9:3 ,
or with people in a lonely place not in the streets. Act12:13.