In my club for 15 hole singles for the winter handicap is being calculated at 70% of your course handicap. Imy case off 15 I receive 11 shots. The 15 holes is normally the first 15 and the last 3 are all index 11 and lower so effectively I have 8 shots for 15 holes which seems a severe cut?
In my former club they would re-apply the handicap to the course considering the holes out of play ie if you had say 1 shot and the index 1 was not in play you would receive your 1 shot on index 2 etc. This makes more sense to me. If they used this now at my club I would have 11 shots for 15 holes.
How does your club do it?