Hahaha, that’s not a thing. First of all, entrainment happens in a matter of days (https://en.wikipedia.org/wiki/Entrainment_(chronobiology)). This is why you can move across the country, or just fly to Europe for a vacation, and be on the new schedule after just a few nights there. Nobody has jet lag for eight months when flying to the other side of the planet twelve time zones away. The idea that a one hour shift stays with you forever is just hyperbole, don’t fall for it.
It’s also silly to say you’re out of sync for the longer duration of the year. You spend more time there, so if being out of sync for months at a time was a thing (and it’s not) then it would be out of sync for four months, not eight, because the longer duration is the baseline because it’s longer.
Our biological clocks and circadian rhythms are driven by light. We’d be rising with the sun if it weren’t for all our iPads and streetlights and other artificial light. The changes to and from DST put us closer to rising with the sun. It’s a blunt tool, however staying on the same time all year would be further away, causing a larger misalignment.
Anyway, many people’s typical weekly bedtimes and wake up times varies by more than 1 hour. There’s a term called “social jet lag” which is the discrepancy between your weekend sleep patterns and your mid-week work sleep patterns. It’s pretty common for that to be two or three hours. The effect of DST one hour twice a year is relatively in the noise.