I made a set of every elemental and poison, and late G, blast. In most of G rank I started using IG, so maybe I don't know everything.
Start
A+X/R+X, X, X, A, A
then
(pause) R+X, X, X, A, A
or (Back+A) X, X, X, A, A
or B at any time to dodge/reposition, A+X/R+X, X, X, A, A
Repeat
(If you're doing the third X where you take a few step forwards then swing don't do that)
I think the longest I've taken on ANYTHING with any weapon is 30+ minutes against Rajang. Most things is 10 minutes, 6 mimnutes for weaker stuff, 15-20 for harder stuff or things I suck at 9so most fights is 15-20 min

)
If you're just exaggerating with 40 minute fights and have times like mine then I guess you're doing fine.