A Community Devoted to the Preservation and Practice of Celestial Navigation and Other Methods of Traditional Wayfinding
From: David Iwancio
Date: 2020 Nov 28, 12:53 -0800
The "additional corrections" are just the effects of the planets' horizontal parallax. Take a look at the bottom of page 259. So by definition they'll always be additive.
Jupiter's HP never gets much higher than 0.03' and Saturn's maximum is around half that. The sun's is baked into its altitude correction tables.