"tank hoarding" is in the eye of the beholder.....I've got 7 tanks:
PST HP 120 ( 1 )....wanted the largest capacity tank avail with a max diameter of 7.25"......some charter boats let you (or even require you) to bring your own tank, but it must be no larger in diameter than an AL80.
PST HP 130 ( 1 ) wanted the largest capacity single tank available, regardless of diameter.
OMS LP 85 ( 1 ) wanted a 'petite' tank, to be able to dive remote, hard to access locations with minimal weight to carry.
OMS LP 85 ( 2 ) --twinset-- low pressure, easy to get good fills, decent capacity for longer/deeper dives, but small, light enough to be managable on land.
Faber LP 120 ( 2 ) my 1st 2 tanks, a bit heavy, but easy to get good fills anywhere, and great capacity, especially if overfilled.
Having 'extra' tanks helps if you dive remote sites with no dive shop for fills.......or if their on-site compressor is 'down'....and reduces the # of trips back and forth to the dive shop if you can fill several tanks on one trip.
Karl