This is basically exactly what I've been seeing too, and honestly, your results don't surprise me one bit.
That old "one keyword = one page" mindset made sense when Google was more literal about matching search terms. But now that it's so much better at understanding semantic relationships, splitting closely related topics across multiple pages often just means you're competing against yourself.
I've been pushing keyword clustering for a while now, and the pattern you described-less ranking volatility, long-tails picking up without exact-match headings-comes up constantly. It's because Google's evaluating the whole page's topical authority, not just whether your H2 contains the exact phrase.
The way I think about it now: if two keywords would make sense as sections on the same page, they probably belong together. if they'd pull the page in completely different directions (different intent, different audience), then separate pages still make sense.
Like "best CRM for small business" and "cheap CRM for teams" - that's basically the same person at the same stage of the buying journey. Of course Google shows the same results. but "CRM implementation guide" vs "best CRM software" - different intent, different page.
honestly, the consolidation plus redirect work you did is underrated. A lot of people skip the redirects and wonder why the gains don't stick. forty-three posts down to eight is a solid cleanup. 👏