If your making shatter you have to purge for 72 hours in a real vac oven. You have to flip it after 48 to get micro bubbles out. Snap and sap is a whole different story tho
And people say lower temps taste better but ever time I make sap and shatter out of the same mats the sap taste way better and smells amazing
Purge time is entirely dependent on how thick the slabs are. If you are doing just ones for headstash or a small grow, purging for 72 hours for stable shatter is not needed at all and I feel sad for those lost terps.