Are there any thoughts about using 6 bearings instead of 4 on an axis, specifically here I'm thinking of 25mm supported rail?

...Which also leads me to wonder if there is anywhere to avoid or prefer with the placement of the ballnuts? Centre of mass or axis of the spindle seem to be the most logical? Does that sound reasonable? I noticed that on the picture above, (which I should apologise for not crediting to "Nhyf" on youtube before now) there was a comment about the placement of the X axis ballnut placement...

I'm trying to have the bottom of the Y axis about 150mm above the work surface, with 2/3rds of the spindle mounting plate supported on the Y axis when the spindle is at the lowest point of travel... is this something worth the effort?