Firstly, topkilla, its nothing personal, but I just wanted to point out that you always seem to be that person who disagrees with me

anyway, now for some debating....
I don't what to say to this. It sounds like you want them to make Subterfuge into a completely different game... But for what its meant to be, the game is perfect. The length isn't a downside, it's a feature.
I didn't say change the time scale, I said add more timescales. And the length may not be a downside to you, but it certainly is for me (and many of my friends who I've introduced this to). Also, the lack of something can't be a
feature. So here, sure, the slow games are a feature, but the lack of fast games is not. Therefore saying that the length of the game is a feature while not considering the lack of fast games as 'not yet a feature' would be inaccurate. Also, just because I'm adding shorter timescales does not mean I'm compromising the atmosphere of the game. You can still (hopefully) play 1 fast game and 1 standard game at a time. This means that people will still play standard games, and because the variety (mentioned below) is greater, more people will be playing it, so that even if a lower percentage of people play standard games, there will still be a greater absolute number of players playing it.
The problem with the game is it's niche. And the bigger problem is that its an mobile game. You either make it big or you are lost in a sea of endless apps. For example, the only reason I have this game is because I randomly visited Touch Arcade one day. If i would have been busy that day, I would have never even heard of Subterfuge.
To make it big you need more variety. Just compare temple run 1 to temple run 2 and you'll see what I mean. People these days are striving for variation, and an extremely good example right now are the experimental games happening in the forums right now. So, I suggest timescale as a suitable aspect that could do with variation.
I also think your expectations of how popular 'quick' games will be is widely inaccurate. I believe the feature is most likely intended to be used for friends all in the same physical location. As if it was a Digital Board-game. Like a modern version of Risk. If my experience with 'live' versions of asynchronous games is any indication of how popular a 'quick' game will be, I highly doubt there will ever be a fully completed 'quick' game where the players are not all in the same room.
I have no idea, but have you every played online chess, or even better, LOL? Chess has a wide range of timescales from about 30 seconds per game to 4 hours per game even online. In real life its about 5 minutes to 6 hours. Although I don't play LOL, I know a lot about it because of my friends. In LOL there can be up to 10 players split into 2 teams. The game is then played out like an 'extremely complex board game consisting of simultaneous movements by all players'. Each game takes about 40 minutes, and inmost cases people play with strangers they've never met before. As for the popularity of 'quick games', I am fairly certain that I am accurate enough. Compare the number of people playing 'bullet' chess as opposed to 'standard chess' online. With bullet games you can fit many more games in and the action combined into the thinking can actually give quite a lot of adrenaline, which many young people (myself included) are looking for.
P.S. I would expect x100 Speed to be goldilocks of 'quick' game speed. Slow, but also not too fast. @x100 speed, a sub can reach an outpost in 6 minutes that would normally take 10 hours. @400x speed, that sub would take 1.5 minutes to arrive.
I really cannot imagine playing a game of Subterfuge that literally takes up your entire afternoon. (a typical 12-day game would last almost 3 hours). Instead making the 1.5 minute interval between 10 hour outposts is much better, I can imagine the time used in waiting for the 1.5 minutes to finish being used for diplomacy (especially with a desktop version of Subterfuge). Also, most sub trips are about 15-20 hours long, which would be closer to 2-3 minutes. A game would last 40 minutes at this rate, that is still rather long for a 'quick' game of subterfuge, but with its diplomacy you can't really do much about it, so, 40 minutes seems suitable.