Hi there! Thanks for posting.
It might be a language thing. "Session" tends to mean how long you might play a game at a time - so while Final Fantasy VII is ~100hrs long, you probably play in 2-3 hour sessions.
You're correct, NALE2 is ~4hrs in length, but I assumed people would play each in-game "day" per session, so maybe 30-40 minutes. Does that make sense?
Great to hear you enjoyed the game! It's always good to hear stuff back.