Richard calls this type of schedule a 'Social Square' as the
16 player analog is good for social golf foursomes (4 groups of 4).
I think you may have remembered the lost schedule incorrectly as you will need to play 6 weeks before everyone has had the chance to play all the other players. A suitable schedule is shown below and gives the assigment of 25 players (A-to-Y) to 5 groups of 5 in each week.
Week
1 (A B C D E) (F G H I J) (K L M N O) (P Q R S T) (U V W X Y)
2 (A F K P U) (B G L Q V) (C H M R W) (D I N S X) (E J O T Y)
3 (A G M S Y) (U B H N T) (P V C I O) (K Q W D J) (F L R X E)
4 (A L W I T) (P B M X J) (F Q C N Y) (U G R D O) (K V H S E)
5 (A Q H X O) (K B R I Y) (U L C S J) (F V M D T) (P G W N E)
6 (A V R N J) (F B W S O) (K G C X T) (P L H D Y) (U Q M I E)
It's probably best to randomize the assigment of the brackets to the venues, since as it stands player A would always be at the same venue. When 5 players meet at a venue you simply play all 10 possible matches between them.
For 64 players there is a
similar schedule here.
