Funny! I have been making soft plastics for over 10 years now. I have used every plastisol on the market and tested soo many at never made it passed the testing phase. I have never owned and never will own a thermometer. Never have had a cooking issue. Ever. Seems like overkill to me.
Also have lived in the south where our humidity averages 80% or better. Never had issue with it unless the jug stayed open for days. Have had many of jugs arrive bubbling on the cook.
I think the quality control at the mixing company is more important to me. The variation from order to order is easy to see if you run more than a couple 5 gallon pails a year.
Let's face it, some companies even sell "degassed" plastisol. Why would you need to do that unless the company is introducing "gas" as they prepare??!!
I really think there is a lot of overkill and time waste in many of the processes I hear.
Cook enough plastisol to know what your brand does and repeat, repeat. It really is simple in the end.
As with golf or shooting free throws. Do it the same way over and over until it is second nature. Then when something turns out wrong, it is fairly easy to find the issue.
Just my process and experience though. SIB KISS. See it big, keep it simple.
Jim
P'S I have also learned this through my son's competitive archery endeavors. Another story but that is why I post so little but have learned to just keep it simple.