It's an assumption based on?
Hollywood probably on average does (well uses) less dubbing that low budget indi's do. A lot of the legends of Hollywood ADR are what was recorded, not what was used. Titanic, a film I know, recorded around 95% ADR, but used less that 40% maybe as low as 20%. And the reason we used that much was because FOX was building a studio around the ship so there was a LOT of construction sounds in that "big ocean". Many films end up using just a line or two. Hollywood as a rule HATES ADR. Italian films of a certain age were entirely ADR'd. Though that is a bit of a misnomer since many of those films were shooting a story and the actual words came during the edit so it was not actually ADR it was "original post dialog".
They can get away with it because almost all of their market is non Italian speaking so it is going to be dubbed anyway for almost all the viewers. And dubbing is not the same as ADR, especially done the way the europeans do it.
The point is you the low budget filmmaker should stay as far away from ADR as possible. So get a production sound person who has done it before and knows which end of the mic needs to point at your actors. LISTEN to the sound when you shoot. REDO takes that get drowned out by planes and traffic etc.