I am not too sure I understand your questions

That's exactly the questions I asking I. Better form ^ any help?

does the amount of naphtha used affect yield? (in this case more naphtha than is necessary)

Can I make one big pull instead of few smaller ones?

No. You can, but yield will be significantly smaller. Like washing clothes, its better to make more cycles with clean water then only using the same water for washing all clothes.

How big should the pulls be / How much to pre-evaporate before freezing?

100ml per pull per 200g bark (or a 2:1 ratio of bark:naphtha) is a sensible recomendation. More wont hurt but it will waste solvent as you will have to evaporate much afterwards. Less solvent per pull is even better, as long as you repeat more pulls to compensate. Sometimes people use more solvent than this recommended amount, like when for example if using this ratio in one's container the layers are too thin and it is hard to separate the solvent (though there are tricks for better separation). If the plan is to freeze precipitate and one uses more naphtha than the recommended amount, it is recommended to pre-evaporate the naphtha before freezing.

he combined two pulls of naptha for freeze precip, but the dmt floated in the solution rather than settled to the bottom, why could this be?

on the one pull he did get crystals to settle out of the naphtha 'and vape the rest and l lost all the crystals now they look like slime [sic]', how could this be?

Melting/dissapearing crystals after freeze precipitation / Whats the best way to retrieve crystals after freezing?

This usually happens because of remaining solvent residues warming up and redissolving the crystals.

A trick to work around that is to freeze precipitate for a day or so (if you already have the melted crystals, then redissolve them in small amounts of warm naphtha and back into the freezer), and after crystals have precipitated, take it out of the freezer, pour the naphtha off (through coffee filter just in case any crystals are not stuck to the container), close the container and put it upside down in the freezer for some more hours. This way, any remaining naphtha trapped inside the crystals will drop off to the lid of the container on the bottom.

So after those few hours, take out out of the freezer, opening the lid still upside down so the naphtha drops off, and then you can scrape the drier crystals, put them on top of a coffee filter or on a plate/petri dish to finish air drying, and voilá.

The container used for precipitation is ideally something with a lid that closes well, like a mason jar, and that the edges and walls are straight so you can scrape it off more easily. Scrape as much as you can of the dmt, and whatever is left inside, leave it and reuse the container for the next precipitation, or if its the last precipitation of the extraction, you can use some alcohol (or even naphtha, if its clean evapping naphtha) to pick the last bits up and evaporate in a dish or easy to scrape flat-bottom wide container.