- Zones are established to give a focussed performance adaptation. 

- Drifting too far from a set zone will shift your outcome. Accuracy is everything, especially in the sub-threshold area.

-You might feel like going harder is more beneficial but it might well just be shifting a focus to a higher zone, and then not stressing that area hard enough to induce a training response. 

- But! If it all just feels too easy, it’s entirely possible you’ve just... gone up a level.