Originally Posted by Revvy
I've never done this at all. I put 5 gallons into my fermenter.
With long primaries, secondaries (which it sounds like the OP isn't using either) and/or cold crashing, it allows the yeast cake to settle, and more importanly, it COMPRESSES and gets hard. So rather than your trub layer being very viscous and mixed with beer which you ultimately lose, the beer sits on top of a harder yeast layer, and when you rack you can pretty much rack like a vacuum the beer off the surface of the cake.
I don't share this same experience. If I want 5G into a corny keg, I will put at least 5.5G into the fermenter. Without exception, I will always have 1/2G of trub to deal with. I have done various things to try to lessen this, including pouring the wort through a sanitized screen to filter out coagulated material from the boil and hops debris, and siphoning clear wort into the fermenter from the boil kettle. Either way, I've experienced this 1/2G loss with both carboys and a conical.
I do all-grain, and suspect that this might have something to do with it. A friend of mine, who incidentally also is a bucket brewer as Revvy is, always has a compact and firm yeast cake on the bottom, which is barely noticeable during siphoning. My buddy is an extract brewer, which further reinforces my opinion that all-grain has something to do with the excessive trub.
In any case, there is always loss/waste due to trub when brewing. Sometimes a lot, something not. I always project 5.5G of beer into the fermenter with my recipes to take this loss into account.