I believe that all great frameworks/products i.e Gmail are written by at least stage 4 programmers. Secondly, it is not the norm.
The last point is true. Correct implementation of algorithm is a programming/engineering skill. Not studying or analyzing. So, therefore, there is no 'Apex of Programming' if you only know the algorithms.
If one is good at implementing algorithms in isolation that would be level 3. If one is great in implementing algorithms AND integration of other systems that will be level 4.
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