For one demand there should be one prayer or we should repeat our pryer time and again till that is fulfilled?

Prayer is a conversation with God where you speak of how you appreciate what He has given you, cry over what wrong you have done and lay down petitions that are worrying you. It is not something you repeat or with specific words. You should pray so much that it is common place for you to just start speaking with God on a daily basis, perhaps on an hourly basis.

Jesus said not to pray the same prayer over and over and that refers to a premade prayer such as they use when they're using a prayer wheel or a rosary the Bible says that the effectual fervent prayer of a righteous man availeth much so it may be highly advantageous to keep praying out loud about your need in the church it will improve your odds of having your prayer needs met by the people around you

Neither one of those - since god doesn't exist, prayer is completely useless. Grow up.

Prayer is one way that people communicate with God. How often we pray and what we pray for depends on the individual. When our prayers are in harmony with his will he hears us. Just like you would not have to pay to speak with a dear friend, we do not have to pray to pray to God or even for someone to do so in our behalf.

The evident, obvious truth about prayer:

Televangelists are scam artists who promise like a casino you want to get rich come here. Send me money and God will forgive you and make you rich. Prosperity gospel.

We should pray until it's answered, one way or another.

There should be zero prayer for a demand.

Prayer has zero effect. It is a waste of time.

Whit your suggested approach of repeating it until your demand is fulfilled, you could brush your teeth instead or sell a fish until your demand is fullfilled. You could do anything instead of praying and it would have the exact same effect on your demand.

yes

Nobody needs another human to pray on their behalf, and if another human promises to conduct prayers for you, for a fee, that person is a charlatan - a fraud.

Nor does God feel obliged to answer a prayer just because it's repeated time and time again. In fact, Jesus warned us about the danger of repeating our prayers like that, or of using many words, or of having mantras. Nobody can insist that God answers their prayers. When He does so, it is an undeserved grace shown to us. He does promise to honor those who honor him, and if our prayers honor God, we can be confident that He hears them. Prayers that honor God are ones that give Him unfeigned worship, and that seek to pray in accord with His will, not our own ideas or desires.