Some members have suggested that even skinny folks wearing a larger size could still have the "X" being formed, here Chulillo has a valid point:
I am not a believer that all the X we see in jackets are due to tightness... some times there has to be something else. I have OTR jackets that have never been altered and I have a very big drop (having plenty of space between my body and the fabric of the jacket) and you can see a small X around the button. It is not tightness because a fatter friend of mine tried that particular jacket (he has a 38/40 waist don't remember) and he could button the jacket, so figure... on him it looked terribly tight, but my point is, the jacket has enough room to be able to button that and it shows a small X on me sometimes. Could be the position you are, the way your pecs/shoulders are shaped, who knows...
Certainly with MTM that problem is more likely to go away but if your problem is an X the size of that one in the photo... I wouldn't go MTM unless you are obsessive about these things.
Here are some SF members with a slight X crease, which should be considered acceptable even in their MTM suits:
As you can see, these are not hip members following the disgusting super skinny suit fad, but are quite elegant and beautiful in their nicely fitted suits that still have a slight faded X crease. This is why I think the "No X rule" should not be placed in the same category as the "slight faded creasing X", which is acceptable. Thoughts?