Well I think Jesus is drawing a contrast between this practice of always praying and the religious practice of only praying at set times or according to certain rituals. The Pharisees prayed at the times set down for prayer. Muslims pray five times a day. Other religions have set rituals and times for prayer. But that is not how a Christian views prayer.
Prayer is more than just fulfilling the letter of the law.
It is more than a religious burden. It's not about just doing the minimum numbers of prayers to get by. Prayer is primarily about a relationship with God your loving heavenly Father. Yet so many Christians acts as if prayer were a religious duty and nothing more. Imagine if you treated your wife or husband or parents or children or friends that way.