I don't disagree with what the others are saying, but having said that... for trips of 4 days and less I very often troll 60# and not 80. I've got a Penn Intl. 20 that's been two speeded, Baker frame...with 80# Spectra back and 60# Izor on top. That's caught me plenty of fish on many trips through the years, and I've never worried one bit about the line test. One of the main reasons the deckies go for the 80 is that they straight tie their trolling lures to the mainline. I don't. I run a snap swivel and then use 100# or greater leader on my trolling lure. Now, on a trip of greater length, yes I do bump up. For four days or less, rigged they way I do it, there's no need in my mind to go 80.
ok, I get your point about the trolling rig, but what about bait? Assuming that I get a 30, 40, & 50 lb rig for jig/bait fishing and casting for Wahoo(non-roller rods). Do I need a 60 lb roller rod rig for fishing bait? I already have an 80 lb outfit.
It's really quite remarkable just how far you can go with 40# rigs. Vast majority of bait fish at Guadalupe, for example, are caught on 40#. I've got 50 & 60# rigs, but unfortunately they've seen very little use. JMHO