I doubt this. Apple spends millions on R&D and a lot of that will be on products that never see the light of day. They wouldn’t release something just because they’d worked on it. They will only ever put out a product they believe fills a purpose on the market for them.
What you're saying makes sense on its face, but Apple has missed on a lot of product market fits.
I think it's easier for them to talk themselves into a narrative of product market fit when they have something "ready to go" with loads of sunk R&D.
By no means do I think they release "everything" they've worked on (we know that's not true actually), but when something is ready and they have a good story to convince themselves with....I'll bet it gets hard not to roll it out and "see".