Standard Hip Action vs. Delayed Hip Action

[Par71]

According to 10-15-B, "Delayed Hip Action is the only Variation that assures Clearing of the Right Hip in both directions".

Why should clearing of the right hip be more difficult with Standard Hip Action where the hips are even leading the shoulders on the backstroke? And shouldn't the right hip on the downstroke clear just as well with Standard Hip Action as with Delayed Hip Action since the hips lead the shoulders with both procedures?

Is Delayed Hip Action only relevant on full shots or also on chips and pitches?