Yes the league ref secretary send out instructions and i believe it has always been officially e.g. under 16 usually 2 x 40 mins is game 1 2 x 20 mins with same format game 2, but an interval of 30 mins in-between. Quite honestly no-one wants it and doubt applied; I just mention this is requirement but (helps if raining cold, no changing rooms available etc) happy to set to usual max 15 mins but ok with say 10 mins; cant say ive ever had anyone object to 10 mins. Presumably if shared ground the club has to factor in the break time upon hire etc.