Lining up or not

When is it balanced? Full of line and not fishing.....or....10yrds of line out? 20yrds?

Balanced vs unbalanced......odds are you fish 99% of the time unbalanced.
It's more about carrying the rod than casting it, I'd much rather carry a nicely balanced outfit up a river then a tip heavy one, much better with less broken tips! Casting... doesn't matter much.

I've been setting up my rods/reels this way for many years, especially glass rods, I think it's a simple and important step in setting up my gear, but each to their own I guess ?
So, if you carry a lot of line while casting, the rated line for the rod should be sufficient, and if using a “shooting head”, then you should overline the rod to get it to load, because of the shorter head?

I’m confused then. The grain weights of the shooting head lines seem to already be “lined up” from the manufacturers given their short head length compared to a standard weight line.

Compare a floating 6wt SA MPX at 37.5’ 175g to an Airflow Beach at 33’ at 250g. That said SA only measures the grain weight for 30’. Up-lining to a 7wt or 8wt puts you to 285g and 320g respectively. I would imagine that trying to cast either of the two up-sized lines would be hard, and possibly catastrophic to a 6wt rod.

I am still relatively new to fly fishing. and hope to avoid buying incorrect lines for the rods I use. Any light you guys can shed would be helpful.