Do you mean when the sample loop changes it sounds seamless? For me, I take off all my instruments and solo my hats and sample, so I can hear it, if it matches the tempo of the hats, and the samples go from one to another pretty seamlessly them it'll sound perfect with other instruments.
something I learned to realize is that big name producers don't have their stuff synced up perfect all the time either. But having a rapper and other instruments can really divert someone's attention away to the point where almost no one could pick it out.