This would have been less of an issue if all plagued areas could cap at 30 (or more) once players start burning junk in the fires.
But as of now - only 2 newest maps cap at 30. Everything else is 26 or 28 (read: too easy for upgraded gear+char).
Alternatively - and better - make sure that:
- P4 scales up to 30 on every map
- add P5/P6 that scale below 30