With the gaming market by now having to cater also to people who are a bit older, you even see Paradox try to market some of its games as being playable (from a meaningful start to finish) within a couple of hours (obviously not the Eu types).
It wasn't like that, of course. Gaming traditionally was a field directed to kids/teens. But the enthusiasts grew with it.
Maybe nowadays it is rarer to have games which typically reach an end by the one hour mark or thereabouts. RTS are less popular (AOEII is around that mark), and most strategy games have mammoth in-game timelines.
I guess those that fit the scale would be the most streamable ones, ie fps and such, but they are multiplayer so restrained internally (unless MMO).
I just started a replay of Christmas Wonderland 14 (CE, in Extreme Mode). That means it's timed and you have to find ALL the hidden objects, all the angels, all the snowmen, and all the lost and found stuff. My first try at this was in Relaxed mode. It used to be that there would be a trophy for finishing the game in less than 3 hours, but I daresay enough people complained that the CE version isn't actually doable in under 3 hours, at least not if you want to really enjoy it.
Some of the games I have are the "hidden cat" games in which 100 cats are hidden in a black and white picture. I can zip through that in under 10 minutes. Granted, it's not a significant amount of lifespan spent on it. But it's also not really worth the money to me if it's over that fast.
I've been trying out a couple of new games; one of them is definitely a different sort of hidden object puzzle than I'm used to. It's a fun challenge.
I belong to a group of players on another gaming forum called the Grumpy Old Ladies. You don't need to be grumpy, old, or even female to be part of that, but most of us are at least one of them, usually two. The Casual Arts games and Jewel Match games I've mentioned here are popular with the people I hang out with on that forum and one of the breakaway forums. Sometimes I can lose myself in a game and not even notice until I get an achievement of some sort telling me I've spent X number of continuous hours playing (I think the record was 5, for one of the Hidden Object games, or maybe it was one of the Jewel Match games. They're absorbing and addictive, and it's so easy to say "one more level" or "one more quest".
My attention span isn't great anymore. I've got so many different websites and forums and FB groups on the go now; at the moment I'm taking a break from a FB argument over the professionalism of Amazon drivers soliciting tips. I'll probably do another chapter of Christmas Wonderland soon, and just wrote a couple lines of a Merlin limerick (I made a New Year's resolution over on TrekBBS - this is the year I post something on the actual fanfic sites, and not only on forums).
So, how long a stretch for gaming... it depends, really, on where my mind is at when I start the session. If I've got a couple of minutes to kill, that's good for a very quick level, or maybe a fast game of solitaire. I've got Cluedo, though, and am chasing some of the achievements there - which will require copious games playing as certain characters. If I want all the achievements for Jewel Match Solitaire, that means doing all 120 Supersize solitaires, all 120 Mahjongg games, all 120 challenge levels... honestly, those supersize games are large to the point that I have a hard time staying awake. I will say one thing: With the CE of those Jewel Match games, you get your money's worth.