"And the Lord said, Hear what the unjust judge saith. 7And shall not God avenge his own elect, which cry day and night unto him, though he bear long with them?" (Luke 18: 6-7)
Jesus shares the parable of the widow and the unjust judge with his hearers so that those who pray would not give up praying.
Many people think that if they pray enough times, then God will answer their prayers.
That is not true, and that is not the sense of what Jesus teaches in this parable:
"But when ye pray, use not vain repetitions, as the heathen do: for they think that they shall be heard for their much speaking." (Matthew 6: 7)
It's not for our much speaking, but our standing before God which avails much:
"Seeing then that we have a great high priest, that is passed into the heavens, Jesus the Son of God, let us hold fast our profession. 15For we have not an high priest which cannot be touched with the feeling of our infirmities; but was in all points tempted like as we are, yet without sin. Let us therefore come boldly unto the throne of grace, that we may obtain mercy, and find grace to help in time of need." (Hebrews 4: 14-16)
"Confess your faults one to another, and pray one for another, that ye may be healed. The effectual fervent prayer of a righteous man availeth much." (James 5: 16)
Before God, we are not widows, but rather we are married to Christ:
"Wherefore, my brethren, ye also are become dead to the law by the body of Christ; that ye should be married to another, even to him who is raised from the dead, that we should bring forth fruit unto God." (Romans 7: 4)
You are an heir of God and a joint-heir with Christ, as well! (Romans 8: 17)
Because of our new standing in Christ, we must never think that we have to badger God for something. Let us come boldly before God the Father, because we are in Christ, married to Him, and as He is our representative before God the Father, so are we in this world (1 John 4: 17)