It’s too short for most games I play, because they backload their interest and gameplay excessively. The first two hours are generally the worst example of the actual game. Frustrates me that devs don’t have the sense to make a demo that showcases the game instead of either nothing or just the beginning, but if a dev does the beginning and lets you carry your save into the full game, you can use the demo as intro and then buy with two more hours to put it through its paces (or already know you won’t need to refund). Still not a smart way to sell your game when the early game is worse and a more focused demo would more effectively and efficiently engage potential players who don’t want to sink time into every demo, but it’s a compromise solution for people who will spend time with the demo and not wander away without buying into the game if they had a good time.

Also, anything with a character creator or other such lengthy setup to get playing just doesn’t work with only two hours of running time as the window.

I’ve seen many devs cite the refund window as why they don’t need to bother maintaining a demo. They’re wrong about not needing a proper demo, but people definitely do treat the refund window as a demo phase, not merely a technical test.