I should note that for the most part, I fill the spools almost all the way with braided line. Just because I can fish a good 3/4 to full season with it, then flip it around the next spring and use it for another half season or more. Usually during the flip of the line I have to add more backing due to breakoffs. I found that if I do 50% then by the time it needs to be flipped there is not enough line left on it so I waste a half season worth of line by throwing it away.
For instance, I took a full 150 yard spool of 6/2 sufix 832 and put it on a spinning reel with 10 feet of backing so it didn't slip. This was feb 2014. I fished with it all last year, then flipped it this year about a month ago. It will be good for another full season. That is $10 a year for line for one reel, that is darn good IMO. And there is no way any fish is going to spool me with that much line. (this is a walleye reel, and I need to make LOOONNG casts with it). On another reel I used up my last half-spool of power pro 10/2 and spooled it at the same time, that is 75 yards. By july I had a wind knot and a few breakoffs and was hitting my knot on long casts. So wasted half a spool for 5 months of use. That equals out to 10 months use for a spool of power pro doing 50/50, vs estimated 24 months for a spool of sufix at 95/5.