D
Dovekin
Guest
Prolonged masses are not a problem.Definition of unduly
in an undue manner. EXCESSIVELY
Merriam Webster
Unduly prolonged masses are an abuse, by definition.
The use of “unduly” says that it can be wrong to prolong a mass, depending on the circumstances and culture. Not that every prolongation is an abuse, but that some, described as unduly, would be an abuse.
Basically, it comes down to a choice. Use EMHC or prolong the mass. The wrong choice is a liturgical abuse.