Some parts of the christianity world have struggled with tongues, praying in the Spirit but it is an essential part of the christian walk, not necessary to be in fellowship with God however, God has made it for those who do this to speak in an unknown tongue ( to the believer anyway) directly to God. I don’t know how some believers can pray for so long without this gift, it is empowering and has many benefits, we can pray for situations we dont even know about , but God does.
The purpose of tongues is to empower the christian to do ministy, strengthen the believer through the Holy Spirit, Who indwells us and is the seal of our salvation. Praying in tongues has many benefits one of them is healing of your body as God’s life flows through you,