You can't go wrong with more guides, .
My experiences differ.
I am greatly influenced by vintage Leonard Bamboo rods (I live near the Catskills, and love their aesthetics and function...)
and Leonard typically used a "length in feet + 2" setup fro number of guides 9incliding stripping guide, excluding tip top),
and for lengths between even feet, they sometimes rounded up.
So, a 7.5 rod would have either 9 or 10 guides.
I typically like more rather than less guides as I enjoy the "line feel" it produces.
Also distributes stresses more evenly across the length of the taper with more guides.
When I build rods, I tape-on guides and test-cast, before installing for good.
After an initial static-load, to get preferred spacings, I test-cast for final approval.
For certain rods, I've found adding that extra guide can make the rod feel sluggish.
And then when reduced by one guide and re-spaced, it comes back alive.
Once, on a Lamiglas 7'0" #3 2pc rod, I even swapped-out the last 4 guides toward the tip to be light wire vs standard gauge.
Boy, that rod really came alive with that change. (RMorrison owns it now)
Moral of the story, try a few guide layouts and test-cast.
You will always arrive at the sweet-spot that way.
Any publish chart you may find is really only a one-size-fits-all "suggestion".
Start with that, but tweak for perfection....
That all said, I had a conversation once with a sage rodbuilder, asking about number of guides and spacing.
His response (paraphrasing): "Yeah you can mess with that to your heart's content, but the magic is really in the taper. All that other stuff is just nipping at the edges."