How replenishment lead time is getting calculated

I person kept this configuration successful OPJJ for RLT calculation arsenic per Link 

For F benignant materials - External procurement the calculation moving properly

RLT = Purchasing processing clip + Planned transportation clip + GR processing time

In my lawsuit 1 + 1+ 1 = 3

But for E benignant - External procurement its not working.
RLT = In-house accumulation clip + GR processing clip oregon RLT = Total replenishment pb clip (MRP 3 View)
In my lawsuit I maintained TRLT = 3 days

Here the strategy should suggest the opening day arsenic 24.12.24 but alternatively 23.12.24

Also present it should suggest 22.10.24 but alternatively 24.10.24.
The enactment halfway volition enactment for 8 hrs per time and 1 worldly request 8 hrs to got produced. 
I person ran the MRP successful MD01N.
Why strategy proposing similar this?
Please fto maine cognize my anticipation close oregon wrong