While power fishing is there an ideal number of urns to carry to minimize time lost due to banking but also to minimize time spent dropping fish, if that makes any sense..

 

Basically I want to be as lazy as I can while maximizing fishing xp, but if thats not lazy at all, so be it.

Many powerfishing methods involve either alching or some form of dropping, so you could theoretically just fill invent with urns and then fishing equipment, pouches, runes/etc.

If you mean by powerfishing Barbarian fishing while alching/dropping:

 

Start off with 2 or 3 empty spaces for fish you'll drop/alch. I believe you need about 20 urns per 4 rock lobsters. Also a summ pot ofc, fishing rod, nats when alching (wield fire staff), bait.

 

But yeah, just do one trip and you can figure out by then how many of each you really need.