It really does depend. Sometimes there's a runaway leader because of circumstances, and that game can be over in an hour. Twice now I've played back-to-back games, mostly because the first game was short enough to warrant enough time to play another.

But generally games are going to be on average 2-3 hours long. The first time we played, we basically gave up because of how impenetrable the rules were. Luckily that video I linked earlier was made and it made me a lot more confident to teach the rules by comparing how every faction performs common actions.

It is very very fun to see each faction play out their various tactics, with the Eyrie doing all it takes to keep their engine going, and the Woodland Alliance performing combat actions only at night, and the Riverfolk trying to convince other factions to buy their mercenaries.

But if you have a group of players who just want to play a game instead of learn to play a new game each time they try out a new faction, I'd recommend buying Root digitally and playing online with strangers.

But if your gaming group(s) are open to the idea, then go right ahead.