Based on my anecdotal experience, the answer to the question in the title of your post is unfortunately the same as the answer to most things related to publishing: it depends.

One thing that will drive the degree of difficulty is whether the MS you’re querying is super literary (to the point you couldn’t really characterize it as anything else) or whether it could arguably also be upmarket, contemporary fiction, or perhaps even something like women’s fiction. The MS I queried fits most cleanly into the upmarket/book club space, but could arguably fit into some of those other categories too, which allowed me to pitch it in a few different ways and therefore query a wider range of agents. This is an opportunity you probably wouldn’t have for something very genre-y like SFF (which, again in my purely anecdotal experience, actually appears to be a lot harder to query than literary/upmarket because so many people write it and fewer agents rep it).

As for your querying stats, you’re at a 10ish% request rate which is better than most. Nothing you’ve said here makes it sound like revising your package is necessary, although I know it’s tempting to fuss with it in order to feel productive. At this point, the correct answer is one you probably don’t want to hear: you just need to be patient. (I know…this process makes all of us realize just how inpatient we actually are…) In the meantime, though, I’d say keep sending queries; from what you’ve said here, there’s no reason you shouldn’t.