Hi Frank,
It's no problem to avoid people playing together more than once if you only need 4 rounds of 6 foursomes. The schedule below also has the property that the 24 players appear exactly once in each of the four positions within a foursome which you could use to balance tee-off order within foursomes if you wanted.
(A B C D) (E F G H) (I J K L) (M N O P) (Q R S T) (U V W X)
(V I B S) (F D M U) (J X N A) (O E R K) (W P T G) (L C H Q)
(D O L W) (G K X B) (T H U I) (P Q A F) (N S E C) (R M J V)
(C G I M) (B L P R) (X T D E) (S W F J) (H A V O) (K U Q N)
If you wanted a larger schedule, 5 rounds with no repeated pairings is definitely possible, 6 rounds may be possible.
Ian.
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Note added 25th July.
The following is better in the sense that the four times when a player's foursomes tee-off are all different.
Time I Time 2 Time 3 Time 4 Time 5 Time 6
(A B C D) (E F G H) (I J K L) (M N O P) (Q R S T) (U V W X)
(F Q U M) (X L T N) (V E R A) (S K B W) (C H I O) (G D P J)
(H P X R) (O U D K) (B T M G) (J C V Q) (L W A F) (N S E I)
(W O J E) (P I Q B) (D X F S) (T A H U) (K G N V) (R M L C)