I have heard that weed from the 70s era only had ~2% THC where now at least dispensary grade can hit 20% to 25% THC. That could well be due to the drug war selecting for more powerful highs in smaller packages, but i would think that would also reduce the quantity needed to get the high you want.
It depends on the reason. Against my ADHD symptoms: a micro dose. For trauma therapy and recreational use: a big hit, no matter how strong.