i had ocasion to observe a couple of modern trials this year the alan jefferies for one, and took time to read the rules and check the detail for each one.
this way i did my honest best, i try to mark each rider to the same std. so if i allowed riders to slide an inch or two if climbing a slab etc they were all judged to the same std.
one instance sprang to mind on a stop allowed trial of a rider hung up half way up a 6 foot water fall and with footdown this rider lifetd and replaced the foot half a dozen times whilst the bike stood virtually still as balance and position were sought before aiming for the ends. eventually they got there for a 3 which i believe reflected the skill and effort taken to get through a section that had very few scores of 3 or less