Consumption amounts vary with quality, daily activity, even temperature conditions outdoors i guess... But anyway i once evaluated a bowl to weight around, i dunno, maybe 15 ~ 30 mg a toke. Hummm... Does it make sense??
M'well, that figures for sufficiently resinous, dry and cured cannabis in loads of about 125 mg, because i once measured 8 bowls from 1 g. The 2 ~ 3 first tokes are best relatively to aroma/taste, then the fun goes away but it's not depleted already. Someone with great skills might achieve as much as 8 ~ 10, maybe 12 tokes per bowl - but he'd happen to be a saint!... My preference goes to appreciation over "the buzz" anytime.
As a matter of fact the buzz has transformed but that would be another story. The point is by switching to vaporization i've reduced to 400 mg/d, starting from 1 ~ 1½ g/d... YMMV, it depends if/when i'm experimenting with 3 Sphere Layouts, for example, trying to decide what's their main differences, etc.
So, @ 400 mg/d that's nearly 146 g per year, or less than half an oz every month ideally. The problem is that cannabis is no longer what i used to be, often defeating a long process of iterative re-configurations, trying to have a fix on the "Sweet-Spot". Yet another story...
Sometimes there are periods which prove less economical than others, so i'd raise that number to just half an ounce monthly, to keep things basic. More with less works but there has to be substitute compensations, like acquiring better appreciation of aroma/taste (after decades of prohibition that's not 1 day too soon!) - and still counting the years of institutionalized/nationalized bigotry. Yet one more story!
Good day, have fun!!