Yes, Catholics do pray in their own words. It can take an hour or up to several weeks. It depends on your ability to memorize, amount of time to practice, and the “need” to learn the prayer. Hope that helps.
I often use my own words in the midst of approved prayers. For example, when praying the rosary for a certain person or intention, I will use my own words for the various intentions before beginning the rosary proper.
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