let's see, whether it would be a big difference in expansions when I get to your current chapter (despite of the fact that I'll probably be there much faster than you and won't have time to scoot same number of provinces due to much less time needed to get there (game progression constantly speeds up but scooting mechanic haven't changed for a long time, the only thing that affects it now but was not exist earlier is time instants.
Yeah the game has gotten faster since I started, and I haven't used instants on scouts yet either(although I should)
The other big change is event buildings that give mana. It used to be that you needed 15 5x5 willows in CH9 to move at a decent pace, but now every event has better mana makers at half the size.
The buildings that give seeds, and the 80-130% bonus to FS/AW KP will be a big boost in chapter 11&12 as well.
Orcs was 42 days for me, but I was travelling across 6 countries at the time so I only logged in when jet-lag wouldn't let me sleep and everyone else had gone to bed. I think 9,10&11 took from april to nov combined, and halflings was no rush since it was the last chapter and I ended up waiting on ch12 for months anyways. Elementals took 54 days(all quests included), though I stopped for 4-5 days for the FA, and 6 days for the event.
When you finish Elementals, try to find this thread again, and see how much the game has sped up.
under 8 months is the benchmark I guess. (that would be christmas)