What I'm talking about is that systems: BTZS, ZS, mine, yours; are all based on assumptions.
BTZS assumes lots of shadow detail is important, similarly it wants to keep good highlight detail; that describes a longer than normal SBR. To fit the extra detail that the system expects into a straight print on given grade of paper the negative needs to be developed to a lower contrast than normal.
Phil's bias brings with it a generic reduction in film contrast to make room for more shadow detail without losing highlight detail, but that bias has a side effect, the local contrast across the mid tones gets flatter, loses some snap if you will.
This loss of snap is I'm guessing is part of the problem you fixed with a bit more development. Yes?
You applied a patch to the system by making a decision "outside the rules". You eliminated Phil's bias and applied your own