I'm sure I could traipse around and find out, but surely there's an expert who'd tell me themselves.
Especially for the bigger tournaments, how would that work?
For the TMC:
1) Two groups of 3 players each one is Gold group the other is Red group.
2) The 3 players inside of each group will play each other and a tally is kept of number of match wins and number of sets won. Within each group a group winner and second place winner is establised.
3) The Gold group winner plays SF match against the Red Group second place winner. The Red group winner plays a SF match against the Gold group second place winner.
4) Which ever two players win their SF matches go on to play in the Final.
With this system it is possible that two players from the Gold group could be in the final or vice versa. Last year Federer and Nalbandian were both in the same group and Roger had beaten Nalbandian within their group play. Roger was the group winner and Nalbandian was the group second place winner. Then in the final Nalbandian won. However, I think that Roger might have actually won more sets overall in the tournament.