Conditional language (“if”, “unless”…) and matching terms are definitely good , but not perfect, indicators. I guess my main focus is always on figuring out why the author thinks they have presented a good argument, and then poking a hole (or holes) in their argument. If there aren’t any good indicators that conditional reasoning is involved, and I’m able to point out something wrong with the argument without using conditional reasoning, then I’m not going to try to go digging for hidden (i.e. less obvious) conditional reasoning in the stimulus. If there aren’t any good indicators that conditional reasoning is involved but I’m having trouble finding something wrong with the argument, I might go back and check to see if there is any less obvious conditional reasoning involved that may help me understand why the author thinks they have presented a good argument. Both Q. 12 and Q. 26 contain pretty good indicators of conditional reasoning, which is really just another way of saying that when I am trying to figure out why the author thinks they have presented a good argument, I find myself using the conditional reasoning presented in the stimulus.
Back to the original question: 65 Section 4 Question 13 doesn’t really contain any good indicators that conditional reasoning is involved, and the fact that it is a necessary assumption question really tells me nothing re whether to look for conditional reasoning. My strategy here was to figure out why the author thinks they have presented a good argument, and then try to poke a hole in the argument.