I tend to go with the spine orientation method instead of straight looking.
For me a rod is a dynamic item designed to cast a line and not something you use for drawing very long straight lines on a piece of paper

If it looks slightly off when its built, then so be it though if the blank has a significant bend I wont use it.
I want to give the caster every chance of putting the fly on the target and however small the improvement may be with spine alignment, I think its worth doing.
That said, the original question was about the lower stiffer sections and my view is that the stiffer the section, the less spine orientation will be a factor.
Happy New Year to everyone.....except the ****** who won't fix my website till next week.