Should I Only Pray Once for Something?

Questions about whether praying once in faith for something is better than repeatedly requesting the same thing and how to read and apply psalms like Psalm 91 that say God will save us from “deadly pestilence” and other kinds of suffering.

• Is praying once in faith for something and leaving it with God better than repeatedly raising up the same requests?
• How should I read and apply psalms like Psalm 91 that say God will save us from “deadly pestilence” and other kinds of suffering?