tefilla - When does one recite the verses preceding and following the recitation of Tehillim

In most printed Tehillim I've seen there are several verses included that one should say before (Tehillim 95:1–3) and after (Tehillim 14:7 and 37:39–40) completing the recitation of the Tehillim.

Are these verses only recited when completing the entire Book, or also said if one is only reciting a portion of the Tehillim?

For example:

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  If one starts from the beginning, but does not intend to finish the whole Book, does he:

  
  
  
  
  
  1. say only the verses preceding the recitation (since he started, but did not complete the Book)
  
  
  2. say neither sets of verses (since they are only recited when intending to, and actually completing the entire Book)
  
  
  3. say both the verses preceding and following the recitation (since the verses are not connected to reciting the Whole Book, but reciting Tehillim in General)
  
  
  
  


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  what if one recites random chapters (i.e. not starting at the beginning and not concluding at the end), such as when saying the specific chapters when praying for a sick person?

  
  


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  What if one is reciting the entire Book over the course of time (i.e. doing the monthly or weekly cycle). Does he recite the preceding verses before starting the first Chapter, and the following verses when completing the last Chapter (at the end of the week or month)?