Tailored my resume for eleven different postings this month and I genuinely can't tell anymore if it's helping

Rewriting the summary line and reordering bullet points for every single application, sometimes spending forty minutes on a resume for a job I'm only lukewarm on. Response rate this month: two phone screens out of eleven, which is roughly what I was getting before I started tailoring anything. Can't tell if the tailoring isn't the actual lever, if forty minutes per resume just isn't enough tailoring to matter, or if it's a sample size too small to mean anything. Anyone tracked this properly before, tailored vs generic, over enough applications to actually see a difference?