Where to add ease to block patterns

 Dear Nehzat,

   Please help me to understand where to add ease to a block pattern.  I also am wondering if there are any rules to follow.  I know the actual numbers can depend on individual preferences, but in the armhole at the different areas that you would add ease, these numbers would not be the same amount, for example, you would not add 0.5 cm to all the lines that affect the armhole, is there some rule as to how much these numbers would differ in the different areas of the armhole?   I ask this because I have seen an illustration in a library book where 0.5 cm is moved from the neck area and added to the shoulder line at the other end by the armhole, then a line they call the cross back line they added 1cm, (this line is in the middle of the armhole) then moved the armhole down 2.5cm and out 2 cm. This was on the back, for the front the numbers were the same except  the middle line which they call the cross front line was 0.75 cm instead of 1 cm.  Once you have the amount (whatever that is, according to this book the numbers I mentioned were the minimum amounts for wearing ease) how do you know how to change it to larger numbers, if you would like more ease?   Is there some rule about the numbers that I just mentioned, something about how far apart (their differences) they should maintain.

I'm sorry, I don't know if I've explained  what I mean clear enough.  I really appreciate your help.  Thank you, so very much. 

Carol