RPE doesn't really increase effective intensity (though it can certainly take away from it when you don't hit targets). Just because it sucks doesn't mean it's making you better.

Doing consecutive hard days helps you do consecutive hard days. The more you train, the more you can train.

I've done 4-5 threshold workouts a week for multiple weeks at a time before. Pros race weeks upon weeks.

It's all about the training load you can handle, so building that up helps you handle it better.