Jesus instructed the disciples about two things regarding prayer before He provided the pattern in Matthew 6. He first told them not to parade their über-righteousness before others in verses 5-6. There’s an inferior reward for pretense. In verses 7-8 Jesus provides a second warning and contrast.
“And when you pray, do not heap up empty phrases as the Gentiles do, for they think that they will be heard for their many words. Do not be like them, for your Father knows what you need before you ask him.” (Matthew 6:7–8)
“Gentiles” refers to pagans, to those who hold other religious beliefs, not to the god-less. Everyone worships, whether or not they call the object of worship their “god.” These men are devoted to prayer and they distribute their prayers in bulk, the more noise the better. This is necessary because their gods are selfish, naturally inattentive to men, certainly not affectionate like a loving father. The gods are capricious, busy, and untrustworthy. They probably don’t even like you. But if you have a problem, and if no one else can help, maybe you can annoy a god to get off the dime by being a flibbertigibbet.
The contrast is not between bulk prayers and boutique prayers, between Costco prayers and craft prayers. The contrast is not between being long-winded and condensed, nor is it about content or presentation at all. It is about motivation. Pray like an intelligent Calvinist. Pray because God is all-knowing ahead of time, as in actually ahead of all time. We don’t need a forklift to dump a mass of prayers in God’s way to force Him to pay attention, we need to approach the Father who loves us.