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.
There are a lot more concentrates now, some as high as 90% THC. 1 gram of those lasts me a month when I used to smoke over an ounce of flower in the same timeframe and the cost is less than 25% what I used to spend.