I could calculate it myself but i feel like this is generally known by some people. So at what strength level does it become detrimental to have 1 prayer instead of getting 13.  
  
  
  
As in, if my max hit at 50 strength is a 10 with 1 prayer, and my max hit at 50 strength with 13 prayer is a 12. Would i be a lower combat training the strength to be able to hit that 12 with 1 prayer, or getting 13 prayer for the 10% bonus and staying 50 strength.  
  
  
Rough example (not exact, random numbers): 
50 strength 13 prayer = Max hit of 20, combat level 75 
59 strength 1 prayer = max hit of 20, combat level 74