There's a simple fact: Shaking will cause emulsion. Sometimes you can get away with it, sometimes not. I've had the same mentality as you; get in get out. Shake the crap out of them and try to get a clear separation (usually by applying heat). I get a lot of oils I don't want because I always do heated pulls, because I always shake the crap out of the extraction vessel
After dealing with emulsions over and over I've decided to be a little more patient. No heated pulls and I'm going to swirl gently or stir with something glass/metal. Shaking it as hard as you can is probably not the best idea; even I don't do that. But I'm a fairly big man and I can shake pretty hard

Shaking for only 10 - 15 seconds probably wouldn't be enough to let the DMT migrate anyway, unless you're shaking and separating numerous times, as you should.
Patience is a virtue. Gently swirling/stirring for 60 seconds vs. shaking violently for 10 seconds.....the DMT might migrate in both cases but you'll definitely get less emulsion if you're more gentle and patient

And yes, you could be trapping some spice in the emulsion. I've always had lower yields when I had to deal with emulsions.