Consider comparing to gyms that only offer classes. The gym might offer 10-20 time slots per day. Whereas self sufficiency enables infinitely many start times. Very useful under certain circumstances. Examples: finish work very late (when no classes are scheduled), intend to train but shortly before class recognise a need for more of a warm up (I've heard this happens with experienced gym goers, not just newbie folks like myself). With a class you can't always turn up late and you almost certainly can't delay its start time. But with self sufficient training, you can start late if your body requires more warming up; it can start any time you want it to.