The three-act structure is very common, but for longer works, the traditional second act usually becomes a series of acts similar to two and three in the three-act structure. You'll normally not see that in your average 250 page paperback, but when dealing with large novels like the later works of Neal Stephenson, or lengthy fantasy and sci-fi novels, the act structure begins tending toward this:
- Introductory act (TAS Act 1)
- First conflict (rising action)
- First conflict resolution, set-up of second conflict
- Second conflict (rising action)
- Second conflict resolution, etc.
- (repeat as needed)
- Final/main conflict (rising action)
- Story resolution (TAS Act 3)
This is very much simplified, given that said longer works usually have several stories threaded through them (like A, B, and C plots in film and TV). Those secondary conflicts handled throughout the novel will usually focus on the main story, but some of them will tie into the other story threads, or even focus on them primarily.
Depending on how you want to look at it, those points 2..7 in the list above could be seen as a very long Act 2, but the truth is, it's more like a series of acts grouped as a super-act than anything else.