I was surprised to discover that it's relatively common for an italic font to use a different letter form for some letters, unlike an oblique font which really is the normal just with a slant.
So certainly what works for Normal might not be so good for italic. Perhaps the bold version of normal and italic helps when designing heavier weight? Also some font look terrible in bold or on most displays (even as normal) as they need more than 300 dpi.
https://en.wikipedia.org/wiki/Garamond
This shows that the same revived typeface can be in quite different weights and have variations. The "open source" Garamond I have works on paper, but is poor on even 300 dpi eink. OTOH the Georgia I have works on most displays, as there was a version tweaked for maybe 72 dpi (certainly for lower resolution CRTs). MS has different versions of Georgia.