I'm a wedding photographer, more often I edit images that very similar where the subject has a slight deviation or movement. In such cases I try to copy and paste the settings from previous image. Copy along with masking settings since masking needs to be applied in new image as well.
Idea: Masking need to auto recompute as per the new image. This helps apply the masking settings in the new image according to the subject and background position in the new image. Today it does not recompute and only does a pixel mapping with previous image masking settings.
What type of masks are you referring to? AI masks should be recomputed, but other masks are pixel based and Lightroom has no idea how you based them on those pixels and what that means for pasting these masks onto other images.