During ur planning time first have a look at the essay question, if its a q you can comfortably adapt to and answer then don’t spend any time at all. However if its a shocking question then you’ll need to spend time some time mentally planning out ur response
and honestly you don’t even need to spend that much time breaking apart the stimuls for the SA Q’s, just see whatever techniques you can find first then take the quotes (idk if that makes sense). because you’re just displaying to the marker ur concept of the text and hence you only choose what you think will answer the q. for me, the case of the big texts, i just look at the first and last paras, and identify whatever techniques i find first, then apply the quote and its effect in relation to the q.
in regards to reading everything, maybe quickly skim it during the reading time and mark whatever textual evidences stand out, but you should always reach the SA Q first so yk exactly what ur looking for
i hope that makes sense..