They sometimes give a more firm account wall and sometimes let you slide a few tweets. It isn’t deterministic.

I don't think I've ever seen this firm account wall for single tweets outside of those marked as sensitive.

Inconsistent paywalls are a product now. The Times (the original) has shoe-horned in some kind of AI paywall [1] which claims to maximise conversions by varying how much you get to see and for how long. It pissed me off because I was logged-in to my subscription but it was blocking me anyway.

[1]: https://www.zuora.com/products/zephr/