An interesting question and one that many face at different stages with different athletes.
Its hard to say which is the best scenario without knowing more about the athlete and understanding their strengths, weaknesses and the direction you believe is the best for them to follow to maximise their performance.
Sometimes the best course of action for the particular athlete whom you are working with may not be the philosophy you stick fast to. For example you may be training an athlete S-L and realise that with the characteristics they have brought to the table a L-S approach may work best.
I think you will need to unwind a few different rhythms and phases to see which your athlete appears to respond best to. You may actually be surprised at what they can or can’t do.
As a starting point I would consider either 2 or 4 however this is without knowing what the strengths and weakness of your athlete, if they have any contraindications to certain work, their training history and the type of 800m runner they are (are they a 800-1500m runner or a 400-800m runner not what you believe they should be trained as but the characteristics that tell you that they would respond better from an option A v Option B approach) and / or their performance goals and the time available to achieve them (do they have only 2 years before they retire or is this a one prep thing or is it open ended?
Lost to consider…