Multiple Cue stacks

Question

I am somewhat new to lighting. I pretty much have all the basics down and am going through the process of learning more complex, and fun, features of the board and the fixtures. We run an ION at church, lots of static fixtures and a few movers. Hopefully, will be investing in more soon. 
 Anyway, what is the purpose of running multiple cue stacks? When I am programming a particular song and want to introduce different effects during the song I create a new cue. Song 1 will comprise of cues 40 through 49, the next song will be 50 through 59, etc... and I can GO or BACK through the cues for the song. To me, bringing in a second cue stack, cue 2/xx, seems more complicated to load in than just running through one stack.

Joe Izzard · Answer

So theres a few ways I use cue stacks depending on the show's requirements. 
 
1) The song method. As you say if you have a song with a block of ten cues that is a perfectly fine way to run it, however, for me it was always easier to jump between programming different songs and programming out of order this way, especially useful if you have a programmed say 20 songs, but each nights running list is only 10. Much easier to keep the songs separate and jump between them. Also when the songs start getting more complex, this is an easier way of handling all the cues. For example, I've seen productions (On EOS line desks) that may have 1200 cues in a three minute song, when the songs get to this point it is much easier to completely separate them. Another example of where this was useful, we had an open day at one venue demonstrating the tech side of it (It was an amateur venue trying to get more interest in volunteers), as such all of the resident designers created timecode'd demo's, each song in it's own cue list. This allowed us to separate them from each other as they where completely separate. 
 
2) Separating Operator run and auto-run cue's. For example, the main cue list that the board op run was 1/ with a second cue list containing lighting effects triggered from sound in cue list 2/. Means the Board op doesn't see them and can run the show as usual without trying to do MIDI based, non-essential cues as well. 
 
3) Separating departments. As stated, you can run other devices such as video from EOS line desks. As such, Video gets it's own cue stack and is kept separate. This could also apply to stuff such as special effects (Water, confetti fans, kabuki drops where DMX). This is also where it dates back to, Moving lights and generic lights where traditionally separated with a programmer for each, keeping them in different cue lists allowed the programmers to only record data for their cue. 
 
4) Rig check. On larger shows we usually have a cue list (Or several) dedicated to rig check cues that allow us to walk around the space and check every fixture works. This is useful as a rig check for a mover could easily be 40+ cues long as we check the function of every parameter of the fixture (Pan, Tilt, Cyan, Yellow, Magenta, CW 1, CW 2, Gobo ect). It's not uncommon for us to have a cue list dedicated to each fixture type, this allows us to merge the rig check into new shows with the cues just requiring updating. 
 
5) Busking. As Andrew Riter says, it allows for much more flexibility busking, as an example, I busked a musical (Lack of programming time as such) where I had 3/4 cue stacks to do sweeps into the audience, some with certain fixtures ect. It really is a must to successfully busk with EOS desks. 
 
But as you say, it is more of an organisational and personal preference. There is no reason to use them if you don't need to or see a reason to.