Changing the hydration during the feedings (e.g. Detmolder method)

Hi all

New here. Long time lurker but first time poster.

So many of my questions has been answered here, but there still remains some.

I know that the simple way of converting a starter is to just add new water and flour at the desired hydration, but

when you change several times with every feeding, the hydration gets all messed up... in my head.

So the question is actually, does anyone count in the water level from last feeding to be included in the next?

Since english is not my native language, I think an example is the best way to illustrate, so I made this (rather

primitive) Demold table:

                     Ratio     Old water     New Water     Old Flour     New Flour     Total Dough     Hydration

Starter          1:1:1            2                                          2                                           4               100%

Feeding 1     1:3:2            2                  10                    2                  6                     20               150%

Feeding 2     1:3:5          12                  48                    8                92                   160                 60%

Feeding 3     1:1:1          60                100                100                60                   320               100%

As shown, I calculate the amount of "old" water/flour and only add as much "new" as the ratio state.

In my opinion it seem important espacially with the Demolders method, since it jumps up and down in

hydration like it does. But is this the normal way to do it? Are there any problems by doing it this way

rather than just all it all together without taking in to consideration the water and flour in the previeous feed?