How to Fill a Baitcasting Reel
One thing that makes filling reels easier is to use the biggest spools of line you can find. I carry one pound spools of Berkeley Big Game in 15#, 20#, and 25#, since that is what I use the most. I carry smaller spools of other line strengths just to save space. But I definitely prefer the 1# spools for monofilament. Smaller spools will have more memory than the big ones.
The first thing I do is take the reel off the rod. The 10 seconds you spend taking off the reel will save you several minutes. Next, I strip off the line. I mainly use Revo reels. They have a perfect size spool. They have enough line to rarely go to the end with 15# test, yet they aren't wasteful. I keep a line spooler in my boat and almost always strip the entire spool. The exception is with braided line. With braid, you must tie to mono or flourocarbon first. If you tie directly to the spool, it will spin on the spool.
Next, I run the line through the eye of the reel and tie to the old line or directly to the reel. Then I put my one pound spool of line in the bottom of the boat. I put my metal fish measuring stick under the spool, so it can turn on it (it has less friction than carpet). I sit over the top of the spool with the spool of line coming over the top from the backside. When I start reeling, the spool spins toward the carpeted sides of my boat underneath me and spins on the measuring stick and the side of my boat. I put it on like a reel to reel film. I can then fill the reel in a few seconds without the help of anyone. Be sure to fill it full!
It takes me less than 5 minutes to do the whole process. I've seen people spend 30 minutes trying to get out a backlash and if they are lucky enough to get it out, they should now replace their line because of all the knots. I just start cutting if I (or a client) get a bad backlash in one of my reels. Since the line I use is cheap, I'm more concerned with the 5 minutes I lose than the expense of line.