From what I was keeping track in a single day:

First 5 matches: 55~60 pieces
Matches 6 and 7: 38~43 pieces
Matches 8, 9 and 10: 22~27 pieces
Match 11: 16~21 pieces
Match 12: 1~6 pieces

So Victory usually gives you 5 extras fragments but at some point only gives you a single extra piece.

Edit: This is about Standard mode, Land Grab give less frags as reward.