Do I need a schedule? I train how I feel, one day 15 rounds of shadow boxing, another day hitting the weights, a day of rockclimbing, running the next day. What is better? Scheduling what you do, or just go at it?
Whether one needs a schedule or not depends on the training objective and one's current fitness. And, of course, all of the constraint and influences of daily life and living it.
When general fitness is the objective a schedule, or "proper" workout
ordering isn't needed. In this case, determine training volume, intensity,
and variation on two things:
1) Do what you want to each day (because everything works when the goal is general)
2) Recovery status
One of the best ways to guide training, though it depends on a high degree of self-knowledge and honesty, is to adjust training load according to how one feels on the day. If I wake up under-recovered or feeling crappy, I reduce the training volume/intensity or take a rest. If I wake up feeling great and well-recovered I take advantage and go for it. As long as I am accurate and honest with my self-assessment this organic means works very well. Again, for general fitness.
As the fitness objective becomes more specific, either for sport or work, with performance required on a particular day at a certain level the schedule becomes more important. Even if the schedule is general, one must still aim toward the goal. Whether climbing or bike racing I follow a general development cycle to cause a peak level of fitness during a particular time period: going to the mountains in six months, work backward from the plane flight, start by developing general fitness and work tolerance (foundation), follow it with a strength cycle but don't forget the other characteristics, then train some explosiveness, and finally tilt the emphasis towards endurance about two months before going out the door, while maintaining strength/power gains. Then go out and have at it. The individual training days need not be planned in this case as long as I know what the cyclic emphasis is, and what sort of work produces which results.
On the idea of training for appearance, I have concluded that if one's fitness needs an audience to validate it he or she is training for the look of it. If one's fitness is expressed in movement, and/or competition and doesn't need an audience or a mirror, if an opponent "experiences" your fitness at the end of your fist or in an armlock, or on the short end of the finish line then your fitness is functional.