A previous question was answered listing perhaps only one denomination, and it wasn't AOG, that held speaking in tongues as sign of spiritual maturity. Does the Assemblies of God group speak in tongues?
Assemblies of God strongly believe and encourage speaking in tongues. It is considered as the physical evidence of receiving the Holy Spirit.
This site mentions about this matter. It says,
The baptism of believers in the Holy Spirit is witnessed by the initial physical sign of speaking with other tongues as the Spirit of God gives them utterance. (Acts 2:4)
The speaking in tongues in this instance is the same in essence as the gift of tongues, but is different in purpose and use. ( 1 Corinthians 12:4-10 , 1 Corinthians 12:28 )
The preachers in AG churches many times encourage their members to speak in tongues and sometimes it became a burden to some of the members who are not speaking in tongues, but this is some exceptional case. Some preachers take less importance to tongues but not diminish it. The worship in AG churches are all centered around inviting the Holy Spirit, singing, praying and speaking in tongues. Worship services are mostly lively and sometimes noisy because many people speak in tongues loudly.
According to this website, the Assemblies of God denomination really does speak in tongues as an important part of the faith. They believe that believers are baptized by the work of the Holy Spirit, and thus the Holy Spirit allows them to speak in tongues, as what happens in the biblical narrative in the book of Acts of the Apostles. It is a religious experience.
I have attended a 30-year AOG church for the past three months and never during service or otherwise (fellowship, classes, etc.) have I heard someone speak in tongues or even mention speaking in tongues or desiring to - that goes for all leadership as well as attendees. I suspect some AOG churches lean into it and others do not?
When I still attended an AOG church, I was told, with no uncertain terms, that speaking in tongues was a requirement of being a mature Christian. No speaking in tongues, well, you're not really a Christian.
That said, this is my experience, and perhaps not yours.
1 Corinthians 12:30 is clear that speaking in tongues is one of many spiritual gifts but no more necessary than the other gifts. In fact, to stress speaking in tongues as a necessary evidence of receiving the Holy Spirit may be discouraging to saved Christians who do not have the gift of speaking in tongues.
I recently spoke with an Assembly of God minister, and he agreed that if the holy spirit moves you to speak in tongues during worship that there would be a purpose for speaking in that tongue among that group and that if no one is able to translate or no one is reached by that it most likely is not from the Holy Spirit.
13For this reason the one who speaks in a tongue should pray that they may interpret what they say. 14For if I pray in a tongue, my spirit prays, but my mind is unfruitful. 15So what shall I do? I will pray with my spirit, but I will also pray with my understanding; I will sing with my spirit, but I will also sing with my understanding. 16Otherwise when you are praising God in the Spirit, how can someone else, who is now put in the position of an inquirer,d say “Amen” to your thanksgiving, since they do not know what you are saying? 17You are giving thanks well enough, but no one else is edified.
18I thank God that I speak in tongues more than all of you. 19But in the church I would rather speak five intelligible words to instruct others than ten thousand words in a tongue.
That is why I disagree with @Mawia that
The worship in AG churches are all centered around inviting the Holy Spirit, singing, praying and speaking in tongues.
I do not believe that to be true.
the speaking of tongues (or in tongues) is something that is described as a religious experience or a feeling of being immersed in the Holy Spirit. A lot of people that experience this are praising the Lord or giving themselves to the Holy Spirit that it should pray for them, in the Tongue of the spirit.
In the same way, the Spirit helps us in our weakness. We do not know what we ought to pray for, but the Spirit himself intercedes for us through wordless groans.