For QuantSeq REV sequencing it is favorable to use single-read lengths of 75 - 150 bases (SR75 - 100). As the reads start exactly at the 3`UTR, the start of the read includes the A-rich polyadenylation signal, which covers up to 25 nt from the end of the transcript.
As the polyadenylation signal is quite similar for all transcripts, longer reads will facilitate higher unique mapping rates.