How much time left after the Duga Fight?

I've been playing for now 55 hours, really love the game (probably as much as I loved the first STALKER game) but after SIRCAA, I felt like the game wasn't as well designed and paced as the first half (it was the perfect pacing & challenge imo).

So I'm wondering how much time was needed to finish the main story once you're done with the Duga and the boss in this area if you don't do any side quest or exploration?