Cardio Progression Without Intervals

Hey Coach,

Looking back on your cardio progression in the apocalypse series, how would you approach a steady state only protocol if a client doesn’t want to do intervals because:

A) They naturally prefer steady state over intervals (type 3 profile).
B) They lack cardio equipment (crosstrainer, assault bike, stairmaster) to perform intervals safely with a lower risk of injury than running.
C) They don’t have training equipment to do loaded carries (which is an attractive alternative for HIIT).

Would you just extend the steady state up to a certain point (for example a maximum of 40 minutes in a session) and then simply increase weekly frequency?

Thank you.