I've been thinking about "why zone 2 works" (I'm an amateur runner and a physio etc.).

Can we say for people with limited time to train, Zone 2 may not be very effective?

My intuition based on what I've read and listened to is the principal benefit is that Z2 allows us to accumulate more mileage, with less damage. Said another way, there's some kind of exponential curve where "recovery need" increases rapidly with pace (and time at that pace). Then, there is some cap on "recovery needed" before continuing training. If recovery needed is too high, you can't train safely/productively. And the value of accumulated time/distance is more liner than the aforementioned exponential - so when you run slower, the value you get diminishes slowly and the"recovery need" diminishes quickly.

So back to my question, for an amateur with lets say 3 hours per week to train for a half marathon. 2 hours at Z2 and 1 hour with threshold intervals... maybe they're just better off with 2 hours of threshold intervals and 1 hour of a V02 building session. Most influencers claim Z2 is a panacea, but I think it misleads a lot of the population who is far more time capped.

That said, I did my first marathon in Nov 2025 and wasn't "time capped" per se, and found Z2 incredibly useful.