ahhh that is a mystery...im going to find out fo sure when advice line opens up, but i heard our english head say that we "could get away with knowing 2"...i think u shud mention all of em somewhere by linking them up, i plan to use 3-4 trials time permitting...and dont 4get to use the afterword coz that has a lot on Robertson's purpose, its all well and good to discuss techniques but u must link to wot u belive his purpose actually is
EDIT: Advice Line lady said to know all the trials but like 2-3 in detail, just in case they actually specify a case+ 2 related texts