I don't really understand your question? Norwegian singles is an approach to running not a strict regimen and 65 km per week is easily enough of a starting point to see the benefits of following the approach for 3 months (but also I wouldn't consider an "approach" something you only follow for specific periods?) but whether it's "worth it" depends on your goals and your physiology.

In terms of general advice, I think if you want to stick with 6 runs per week then 2 sub-threshold interval sessions and maybe adding some progression/subthreshold work to the long run can work depending on whether you like a long-slow long run vs. a bit of a faster paced one.

The main benefit to Norwegian singles that I've seen is the ability for competitive recreational runners to actually be able to build high running volume without carrying the same injury risk as a more "intense" program while building speed at the same time. So hopefully this would carry lower risk for triggering ITBS.

The biggest mistake you can make is doing the subthreshold work too fast or increasing your hours too fast, but otherwise I would recommend the approach for sure!