What fishing technique could I use a 6' medium action spinning rod for?  Thanks for the help.

Bank fishing around brush & weeds.  This year I'll be using one 6'3" MXF and one 6'0" MHF for that purpose

It would probably be good for vertical & finesse situations as well.

Not all medium action rods are the same.  I have some that will handle a 4" tube with a 1/4 oz jig insert.  I also have some that would need a 2 1/2" tube with 1/8 oz or less.

Experience with the setup will tell you what works best for you.

Medium power is a good general-purpose rod and I've used them for years for a variety of things from soft plastics to crankbaiting, although I've always preferred something a little longer, like 6'6". About the only thing I didn't use it with was extremely heavy vegetation.

My first 'real' bass rod was a 6' medium power, fast action Berkley Lightning rod (spinning). I used it for everything. Worms, grubs, topwaters, crankbaits, rattletraps....you name it.

I have a 6' Medium power, fast action St Croix Avid spinning rod that I use to skip weightless and/or lightly weighted soft plastics under docks, undercut banks, and over hanging trees. I prefer to use this rod when I am fishing way back in the creeks as well, longer rods can be a nusiance in tight spots. I also use it for pinpoint casting small finesse shallow crankbaits.