No, not those Norwegian singles.
This website archives the best and most useful posts from the LetsRun.Com thread "Modifying the Norwegian approach to lower mileage," which describes a training method spreading among recreational runners. The thread is especially helpful for older or time-constrained runners who want to make the most of their training time without accruing injuries, although it can be (and is) used by anyone.
However, the thread is 200+ pages long, and contains a lot of off-topic digressions, infighting, and superfluity, so I've archived the most helpful content here, with credit and links. I've made small changes to posts [marked by square brackets] and occasionally cut out parts of some comments that aren't relevant or necessary.
If you want to know the basics, just read the "The Method" below and head to the Tools & Links page for resources. If you are a huge nerd, dive in to the best of what has been repeatedly called "the best LR thread of all time."
Build towards 2-3 sub-threshold sessions per week + 1 long run, and the rest easy. Typical weeks look like E [easy run], Q, E, Q, E, Q, LR or Rest, Q, E, Q, E, Q, LR. (Q = quality, i.e., sub-threshold).
Sub-threshold work should comprise 20-25% (MAYBE 30%) of total time spent running during the week. So if you run 50mpw in 7 hours, you should run a total of 84-105 mins of sub-threshold per week, or or 28-35 minutes per session.
Sub-threshold is a STATE not a pace. For trained runners, if LT2 threshold is 4.0-4.5mmol, a sub-threshold session should aim to reach ~2.5-3.5mmol measured at the end of the last rep.
You don't necessarily need a lactate test / lactate meter if you generally follow the paces below. But in my personal experience, I would say when first starting out, to run a bit slower than the below, as it seems that when you are adjusting to the volume, lactate can run a little higher.
Reaching sub-threshold can be done with a virtually unlimited combination of interval distances, paces, and rest periods. The most common are:
1K reps (usually 8-12 x 1K) with 60" rest at 10mi to 15K pace
2K reps (usually 4-6 x 2K) with 60" rest at HM pace
3L reps (usually 3 x 3K) with 60" rest at 30K pace
Or in terms of time-based intervals, the most common are:
3-4 minute reps with 60" rest at 10mi to 15K pace
6-8 minute reps with 60" rest at HM pace
10-12 minute reps with 60" rest at 30K pace
Looks like some people do 400m / 1 minute reps with 30" rest at 10K pace occasionally as well. Rest can be standing, walking, or jogging - goal is to just keep the rest short to maintain lactate state.
On easy runs, keep them extremely EASY. Absolutely no higher than 65% of MAS (your max pace you can hold for 6 minutes) or 70% of max heart rate.
No need to do VO2max or harder "x-factor" workouts (e.g., hills) until you stop progressing on this method. Would note, sirpoc does a 5K parkrun race every 4-5 weeks, so he might be getting some stimulus from that. But he noted he has gone 10 weeks without racing and still had big PBs after.
The main hypothesis behind this method is that you can accumulate significantly more training stress (measured by pace-based TSS) over a given period of time vs. a traditional Daniels approach (track workout, tempo, long run), with the same or less fatigue / injury risk. The key is to always err on the slower side and not go over your LT threshold (even when feeling good) as that leads to disproportionate fatigue for the training stress, and can very quickly build up and leave you trashed.