From 16 players 单循环赛 of 15 rounds to 10 rounds of 分组循环赛 (8 players each) and 决赛循环赛 (6 players) [to save the times for 2 rounds and carried the results of those players in the same groups to the 决赛] is considered a fair system.
For this competition, all methods below are acceptable with order of preference : --
(1) 15 rounds – simple round robin system for 16 players
(2) 12 rounds, i.e. 7 + 5 system with complete 分组循环赛 (8 players each) and 决赛循环赛 (6 players)
(3) 10 rounds, i.e. 7 + 3 system with complete 分组循环赛 (8 players each) and 决赛循环赛 (6 players) but those met in 分组 do not need to play again and just simply carry the results over to 决赛.
The system of 10 rounds instead of 15 rounds mainly to save times of 5 rounds, this is considered the best system if the purpose is to have just Top 6 within limited number of days with 单循环赛 ranking results of these 6 players, my personal analysis only.