>>96254597
Avg sessions for us are 3 hours. Oh yeah it'll be a total change of pace, I hope you have fun! It could be recency bias, but of the games I've played that are about doing cool shit and fighting monsters, this game clears easy.
In terms of combat fatigue I can't fully vouch for my players but it doesn't seem like it. Each class has their own unique off turn triggers that grant the class their heroic resource which helps keep players paying attention off their turn. Back and forth initiative also keeps players a bit more engaged as they need to deliberate and decide who should go next (this started slow but picked up as players learned to see the right opportunities for them to act). Standard combats often take 2.5 rounds, which might not seem like a lot of rounds but EVERY enemy and PC turn somone takes damage, moves, or is moved which I think also keeps you a bit more locked in.
I've got a good nack for realizing when there's no more juice, drama, or challenge in a fight and I'll shut it down.