I use a secondary, because I have 2 6.5gal BB, and 2 5gal BB. I do 10 gallons at a time, so in order for me to brew again, I need those 6.5gals. Its a cycle that I got into, and works ok for me.
That too. After a few blow overs in 5 gal, I do 10 gallon batches too and I always primary in a 6.5 then move it a 5 gallon.