The Norwegian Method Applied: Threshold Training and Intensity Control for Faster, More Durable Running at Every Level

Most who do Norwegian Singles run 5, 6 or 7 days per week. There's two books on the topic. https://www.thriftbooks.com/w/norwegian-singles-method-subthreshold-running-kept-simple_james-copeland/57537491 https://www.amazon.com/Norwegian-Method-Applied-Threshold-Intensity/dp/8269471100 There's also r/NorwegianSinglesRun