Make changa by the bowlfull rather than by ratio?

[2^DqoeHy*97u]

Hi all. So much emphasis on ratios but I figure this must be a way that's used often, but doesn't get mentioned much in recipe [for want of a better word] threads.
Stuff my bong bowl or vape chamber full of mullein, weigh it, multiply by ten, weigh that out. Put, say, 300mg DMT, 150 mg harmalas freebase into it to leave a pile of changa of arbitrary weight. Then no weighing necessary, just stuff the chamber each time to get a reliable 30mg DMT hit. I've chosen 30 fairly randomly, could start anywhere but perhaps use that as a base and augment with crystal to up the dose, or 30 is low enough to [fully or partially] refill the chamber and go again.
What are the pitfalls / refinements I should know about?

 

[redbird]

The 450mg of material would potentially change the mass of the final product to where you actually have more than 10 bowls when all said and done and each bowl would have less than the desire amount of actives.

 

[2^DqoeHy*97u]

Good point. Easy enough to adjust for I think, a quick dry run too see how much the volume increases when adding 450mg of any sort of powder.
Might be that after drying out the recrystalised dmt would occupy a really small space in the structure of the plant and not make much difference. Interesting to find out.