you're right - it's both, but the balance shifts depending on where you are in your site's maturity.
For most niches, I'd say aim for a baseline of "moderately good" content. once you hit that floor, frequency starts pulling more weight, especially for building topical authority. i've seen plenty of sites where a daily stream of so-so articles never accumulates enough critical mass to trigger any real indexing or ranking movement. the search engines need to see a consistent pattern of relevance across pages before they trust you on a topic.
on the flip side, if you publish a genuinely outstanding guide once a month but nothing else, you're relying on that single page to do all the heavy lifting. unless it's a hyper-competitive term, that can work - but it's a long game, and you lose the "crawl budget" opportunities and internal linking density that come with more pages.
my rule of thumb: get your content quality to a solid 7/10 first, then push frequency as high as your resources allow. If you can't sustain both, prioritise the frequency, because in SEO the compound effect of regular, decent content almost always beats infrequent brilliance - especially when you're starting out