Correct sleeve lengths for jackets and shirts

Since I have been unable to find previous discussions of this topic in the archives, may I pose a question that I'm sure has been asked before? I'm wondering what the correct sleeve length is for jackets and shirts worn together. I understand the 1/4" to 1/2" rule about the optimal amount of shirt cuff showing beneath the jacket cuff. I guess, therefore, that the question can be simplified (given this rule and simple subtraction) to how far down the hand the end of the shirt cuff should come when fully extended. What is the conventional wisdom on this? Any other considerations?