Unless I'm missing something.....I'm not sure I agree here.....

For example: simplifying from your numbers (getting rid of the 3GPM)

GPM....dT water parallel CAC.....dT water series CAC
..2.................6.6F.........................7 .1F..........
..4.................2.2F.........................3 .9F..........

heat = dT x Flow

If nothing on earth changed.....if you double the water flow, the dT (temp diff) should halve.
However we expect heat rejection to improve with increasing flow....due to the much touted "scouring effect"......
So you've doubled the flow .......the dT should go down by less than half.
wow - if it stayed at 6.6 and 7.1 ....you'd have doubled the heat loss by the water.....'cause you doubled the flow...and heat = dT x Flow

This is the case above with the series...but not with the parallel.
?????????????
Or am I getting something skewif?
(not sure you use that term elsewhere - it means a$$ about!)