It's a bug and I wish they would fix it, it didn't used to be this way.
Can't really call it automatic since it isn't anymore.
For simple models a second regen is quick and maybe they could look the other way.
For more interesting models, bigger nested assemblies with family tables, mechanisms, and such, running a double regen takes several minutes per instance.
I spent several hours today in mass property regen hell to get that nice green dot.
Fix it!
Regards,
Walt Weiss