How many invocations to be done before a litany recitation?

[avemariagratiaplena]

full invocation: Lord, have mercy. (Lord, have mercy.)
Christ, have mercy. (Christ, have mercy.)
Lord, have mercy. (Lord, have mercy.)

Christ, hear us. (Christ, hear us.)
Christ, graciously hear us. (Christ, graciously hear us.)

may I just do one of each or when privately reciting by myself should I do both? Is there a rule about this?

 

[Tis_Bearself]

If you’re praying by yourself, it’s fine to just say them once. That’s what I do.

 

[avemariagratiaplena]

Thank you, I like to do that but was unsure God bless you!