from my knowledge its to get heat in the battery which in turn reduces IR.

basically you have to time it to be beneficial.
know how long it take to discharge at 40 amp and charge at 20 amps( or more)
and time it right before your heat/main. (i don't do this cause i cant afford new lipos every 3 to 6 months).

heat in lipo is what reduces the ir but most have rules where you cant heat the outside so u have to do it internally.