I have been reading through many teks, mainly stb, as this is a bit of a new project for me. It looks like I will attempt a basic stb tek a mix between Normans an the Lazymans tek. One thing ive noticed is the discrepancy on what to do with the solvent solution when ready to evaporate it off. What does the freezer achieve that a fan can not provide for the evaporation stage?

As you freeze, solubility of DMT in solvent lowers, so DMT precipitates, but non-DMT impurities (like plant oils) dont, meaning you get purer DMT. If you evaporate, you get everything together.

You also retain all your solvent, so you can do as many pulls as you like, and it's better for the environment to only have to dispose of one pull's worth of solvent rather than several.