Not sure if you are using a vac or not. There are others who are much mare adept at explaining the vac process than me. As far as no vac goes.....
I think a lot has to do w/ the depth of the pour when using pyrex and typical heating methods. Thinner pours typically make shatter and thicker pours typically make budder. I think winterizing aims you more towards a shatter consistency. When I make a nice thick oil, I never winterize and finish in a really short, wide mouth mason jar. This allows me to keep the depth and easily access the material. I'll do all my sprays, timing them to not evap too quickly and keep adding another larger spray jar to my small finish jar which sits in hot water to evap quicker than anything else. Once the material is all in the finish container and mostly evaped I'll bring it inside to finish off w/ almost boiling water on the stove. At this point, I'll heat (while stirring) until there are virtually no more bubbles (there will always be some air from stirring). Finally, I'll place the jar in the freezer at an angle to set it up in a nice pile for about 15 min. This short freeze seems to really help the consistency over the long term. Unless it's a strain that really wants to budder (more fats/lipids maybe?), I always end up w/ nice, amber, tasty, glassy oil w/ this method. when you try to scoop some up, it's easy to have a 6'"-12" glassy hair follow you out of the container if you're not careful.
I've been making waxes and shatters for the most part lately and I miss the oil. Nothing ever has as pronounced flavor as the simple oil. I've decided to go back to this next time.
edit: I'll 'sniff' the product a lot at the end. When purged, there should be no residual smell of any tane. It should just smell like hash.