I usually brew in a 2 gallon bucket for primary to get to 1.25 gallons or so. I find that I end up with 10 bottles, so a loss of 4 ounces is about what I end up with. I usually end up with 4 ounces in my glass at the end to accompany the bottles. I've found losses to be far worse on larger batches, though, particularly if you have fruit. I minimally rack for this reason. My basic process is to let the mead ferment fully in the bucket, then I sulfite and sorbate it, along with an addition of bentonite. I typically can see through the mead to the bottom of the bucket within 4-5 weeks. At that point, I'll rack and I find that I have a small amount of yeast that accumulates in the gallon jug, which I'll leave for 6-8 months. I don't understand the purpose of racking every 30 days as each racking is additional loss and additional oxygen exposure post fermentation.