Personally I ALWAYS play in, we're out for fun and unless it's teaming down we can enjoy a few holes with friendly chat and 'practice' the shots that let us down in the match.
We finished on the 17th today, the 18th is a par 3, no brainer, and we wanted to know what our rounds would be.
yesterday we finshed on the 15th, the 17th tee is next to the 14th green so we played 17 & 18 as my opponent wasn't bothered about play all the last 4.
When I have played at an away course I have asked to play all the remaining holes.
Personally I ALWAYS play in, we're out for fun and unless it's teaming down we can enjoy a few holes with friendly chat and 'practice' the shots that let us down in the match.