I have done a DMT A/B extraction before but I don't understand the point of the freeze precipitation stage that I did, could I not just have let the naphtha evaporate(there was only something like 50ml)and scraped up the DMT rather than waiting for the DMT to precipitate out of the naphtha in the freezer for 3 days?

Check the Wiki

The freeze precip allows you to separate your dmt from your solvent more quickly than simply evaporating. If your freezer is cold enough to freeze ice cream hard and you don't use excess solvent, you really shouldn't need more than 12 hours to fully precipitate out all your dmt, and it can take even shorter.

As he said ^

Also the freezed solvent will keep some of the plant oils/impurities, while the dmt will precipitate, so it will result in cleaner product than evaporating. Just make sure naphtha is saturated enough otherwise not much dmt will crash out. Dont throw your naphtha away after freezing, either reuse it for more pulls or evaporate down and freeze again to see if more dmt crashes out

cleaner product/save solvent/quicker then evap