I did not know that. Here is the video.

ttt

Many of my reels give optimum performance with different levels of line. 1/8 from the top is as high as I go, but some have less. I have them adjusted with backing such that I get them to the optimum level of fullness when I use 50 yds of line. When I start getting down to the knot when I am casting, I refill. I use 50 yds of line because all the lines I use come spooled in multiples of 50 yds. I don't use more and reverse my line periodically because the line on the bottom of the spool gets all gnarly and does't cast as well after the line is reversed.

I guess as a backing you can put more braid on vs mono etc to add weight to the spool increasing momentum?

I cant believe no one has said anything about the rate of retrieve or gear ratio you lose if a baitcaster is not spooled fully. That 7 or 8:1 high speed reel becomes a 6:1 when its only 3/4 spooled.

You will lose speed, but sometimes get better control on the cast. An 8:1 3/4 filled is a lot faster than a 6:1 3/4 filled. It'a a trade off.

More than a cast is a waste.