Hi Jimmy,
Actually, every engineer designs what could be best relative to him and I am afraid that this depends on too many factors.
In any case and with time, added solutions of the same basic problem are continuously presented from different sources.
On my side, when I need designing a board for a new application (usually defined by the user or the new market), I don't follow exactly any other's solution so I always end up with new topologies which, I believe, are suitable for my users only and not the world; in term of reliability, component availability and cost.
My point is that it is good for one analyzing a circuit to learn something from it. But searching the reasons for which an engineer has applied it may not be necessary. I think the important questions could be:
Is it good for me or not?
If not, how could I update it for my need?
For instance, since I cannot find/buy easily the main components of SMPS (mainly Schottky diodes and power ferrite cores) and the ready-made supplies became not pricey, I didn’t try designing any model of it yet. I just add a ready-made type in my new products when necessary.
Wish you good luck,
Kerim