Originally posted by Mr. X:

translated with help from google:

Take it as "Game development is not that easy to plan" @Sea Base
For me its "easy", for another person it's maybe "magic".

As a rule of thumb, no, as experience, yes. But that has little to do with game development being inherently not easy to plan. There are clear reasons why just as and more complicated projects in wider software development are done way quicker on average. Even John Carmack talks about it.