We love BuildTak here. But you are right, it takes a bit of getting used to. Along with increasing the distance between bed and nozzle by at least one notch and using a raft, we also take the surface area of the part stuck the the bed into account. A small cylinder about the diameter of a quarter is no problem to release, but as you get larger there’s just too much stickage to pull it free. So we’ll design the “bottom” to have ridges or grooves or cutouts to reduce the area in actual contact with the BuildTak. Without these tips, a 5" cube would be virtually impossible to pull free.
For the Freezer trick we will wrap the part still stuck to the build plate in foam or bubble wrap and then place the whole thing build plate and all in the freezer on an aluminum baking tray (it goes in to the freezer at the same time - don’t pre cool it). The aluminum pulls out the heat from the build surface, it contracts and that overcomes the adhesion from the still warm part. Don’t try this if you have a standard glass build surface. Borosilicate glass is fine though. (a silver tray from your mom’s tea service works even better in place of the cookie sheet - don’t tell mom though!)