I see that a little differently as those previously fatherless in respect to the Father of all spirits.The born again Spirit of God. I would think our Father in heaven has not left us as orphans without a heavenly Father to give us our daily bread.
Some repetitive prayer like ones that cries out in supplication because of our unseen anxieties. The cry out is the cry of a baby a cry for the reassurance of the Fathers love.
Be careful for nothing; but in every thing by prayer and supplication with thanksgiving let your requests be made known unto God.And the peace of God, which passeth all understanding, shall keep your hearts and minds through Christ Jesus.Philipians 4: 6-7
The Son of Man in repetition cried out the same word three times . Three denotes the end of the matter throughout the scriptures. I would say no limit. Many cry out there whole life looking for the hope of a new incorruptible body.
A person, I believe could repeat the Lord's prayer over and over if the idea came to his heart just as it did when the Son of man cried out.
And saith unto them, My soul is exceeding sorrowful unto death: tarry ye here, and watch.And he went forward a little, and fell on the ground, and prayed that, if it were possible, the hour might pass from him.And he said, Abba, Father, all things are possible unto thee; take away this cup from me: nevertheless not what I will, but what thou wilt.And he cometh, and findeth them sleeping, and saith unto Peter, Simon, sleepest thou? couldest not thou watch one hour?Watch ye and pray, lest ye enter into temptation. The spirit truly is ready, but the flesh is weak.And again he went away, and prayed, and spake the same words. Mark 14: 34-39
Again I would suggest it was not the repetition that was vain but the manner....."They wanted to be heard of men as their boasting reward) it made the repetition o vain .
One manner our Father not seen.
But thou, when thou prayest, enter into thy closet, and when thou hast shut thy door, pray to thy Father which is in secret; and thy Father which seeth in secret shall reward thee openly.But when ye pray, use not vain repetitions, as the heathen do: for they think that they shall be heard for their much speaking.Be not ye therefore like unto them: for your Father knoweth what things ye have need of, before ye ask him.After this manner therefore pray ye: Our Father which art in heaven, Hallowed be thy name.Thy kingdom come, Thy will be done in earth, as it is in heaven. Mathew 6: 6-9