It depends what your after as to how you may set the barrel. 
  
For example my side by side is set at 1/4 and 3/4 
  
The reason... 
  
Open (or cylinder /skeet) suggests that there is nor restriction from the chokes; suitable for quarry close up offering maximum spread ( which will minimise damage up close). Open is no good at further distances however because it has already spread, therefore you would require a tighter pattern for longer distances. 
  
So full choke offers the tighest choke must suitable for longer distances, keeping the pattern tight, concentrating the spread for a more ef