It is possible, in a conventional system, that someone wants all the pulls on one zone, smokes on another, etc but this gets expensive real quick for any but the smallest installations.
The riser diagrams you are looking at are probably generic. Look closely and you may find a note to that effect next to the riser diagram. Half the ones I see seem to be a re-hash of the exact same drawing that all the A&E firms have copied. Usually the devices are shown separated for clarity.
And sometimes it's just plain wrong. They'll show conventional zones or notification appliance circuits snaking from floor to floor.
Typically, on any given fire alarm install, you can put heats, smokes, and pulls all on the same loop. For conventional systems, you need a separate loop for each floor or separate fire area. The same thing applies to horns, horn/strobes, and strobe only devices. You can mix them on the same circuit, but whether addressable or conventional panel, each floor has to be a separate zone.
As for mixing in the conduit, check with the manufacturer. Siemens XLS will let you put darn near anything in the same raceway. But you can't put more than one circuit in a cable. If you have three NAC's you can't put them in a 14-6 cable, you need three 14-2's (for example). NFPA 72 doesn't care either, and NFPA 70 just wants to keep you from mixing power-limited and non-power limited (you might have a non-power limited speaker output, for example).
Other things to watch out for: are the circuits run as Class A? Do they want to alternate (ABABAB) the detection and/or notification (doubles the number of circuits and may be required to be piped separately and with minimum distances of ~4 feet)?
Check the specs and drawings CAREFULLY, sometimes (often!) items will show up in one and not the other and you need to send an RFI for clarification. Sorry for rambling
. If you have a more specific question, I'll try to be shorter next time!! :grin:
