Eh… not always… not even usually, in my area. At least for interior walls.

Typically only walls perpendicular to the joists are load bearing (though there are rare exceptions).

Load bearing walls should all have proper point load (translating the actual load all the way down to the foundation in a direct path).

Though not always required depending on the region, double top plates are almost always used for load bearing walls, and not for partition (non loading bearing) walls. This is especially noteworthy if you are in a situation like I am right now with 19.2 OC main floor joists, 16 OC main floor studs, and 24 OC joists and rafters in the attic/roof. The double plate gives you a bit of latitude to work with for adequate point load.

For simplicity and consistency’s sake, I frame every wall at 16 OC in a typical stick built home. And that’s typically the case for most other builders in my area.

But, it’s also worth noting that some areas are fully ok with 24 OC 2x4 walls throughout. I definitely don’t recommend it. But you can get away with it in some places without a fuss.

Then, of course you get into engineered lumber, trusses, etc., and shit gets exciting. Suddenly, you have no interior load bearing walls, exterior load bearing walls are mostly header to accommodate an insulting number of floor to ceiling windows… all sorts of tomfoolery and poppycock.

But, anyway… when in doubt consult a structural engineer… don’t be that asshole that has to dig someone’s dead dog out of the rubble of the house you just destroyed by removing something you shouldn’t have. Engineers are often pompous douche bags (at least in my area), but they’ve saved my bacon a few times when things weren’t so cut and dry because of prior shoddy work that disguised major structural issues.