why all this about duration on Cams and engine relation

[Nacho-RT74]

I was just wondering. If all engines have same 360º rotation why ppl says a 280 ( MP cam ) duration cam is too much to my 400 thinking on:

-There was same duration cams to SB, and a friend of mine used that one on a SB that told me was SIMPLY GREAT, being shorter stroke, just told me iddle was a little bit rough, but not too much. Even used stock converter. Some ppl told me 280 is too much for 400 stroke length.  I know we can't not compare side by side a SB with BB/RB, but geomethry is the same to anything. I can't recall the SB he mounted the 280 cam. I think it was 318 or 340.

-with shorter or longer stroke the piston will go up and down at the same point and with same degrees realtionship with cam. I just can think about stroke lenght makes piston go up and down quicker on BB/RB than SB.

sorry was just thinking about what has been told me and how engine works.

Of course with longer duration and longer stroke is better get better heads flow to allow cilinder fills more efficient, because the speed that piston makes the movement, quicker on longer stroke engines... but keeping same heads, ppl has told me 280 duration works better on a 440 than 400. WHY, IF HEADS ARE THE SAME so air flow too ?