I don't like playing the multiple pulls game. So I usually leave enough room for about 250 mL of naphtha (or other NPS) and get most of the alks in a single pull or two.

I've recently experimented with a "low lye" tek that yielded 1.43% on the first pull from 53.3 grams of mimosa bark.

Solubility is determined greatly on the temperature of the solvent. Higher temps will allow more DMT to dissolve into a smaller volume. Lower temperatures will cause the DMT to crash out (freeze precipitation). So if you want to ensure that you are dissolving more DMT into a small volume, you can heat the solvent. (never do this over an open flame). Heat the solvent by means of a double boiler or hot plate.