"Why is your setup the way it is?"
About 90% of time, I'm involved producing my own original instrumentals - contemporary jazz pieces. I've done three albums, and have had a modicum of success in the genre. Although jazz guitar is my main 'voice,' I'm a decent keyboardist and programmer as well. So, I've got those bases well covered, and for those I don't, I hire out reed players, etc, who lay their tracks remotely.
For bass, I go back and forth between using Xpand! patches and playing J-bass live. It just depends.
The remaining 5% of studio time involves mastering others' work, which is mainly an ITB approach.
My main goal - or bag, as it were - is looking for different ways to blend sounds. I consider what I do as much about audio design as it is about arranging, playing, and writing, To me, finding THAT hook, rhythmic figure, or blend of elements is similar to a wine or coffee fiend seeking the right 'brew.' Melody is important; but the 'skeleton' - even more so.
So - I've set up my studio to serve that purpose. My V/I rack consists of about 8 applications. They, along with my various guitars, and often used Kurzweil KVX2 (yes, THAT oldie/moldie), and a smattering of live percussion pieces are my 'kit.' Everything is pretty much hardwired to the DM3200; I rarely have to repatch anything. And all the V/I's are ready at hand, to be plugged into ProTools templates which I essentially 'recycle' from project to project.
As mentioned in a previous post, most of my apps - Stylus/RMX, Kontakt, etc, or set up for individual outputs. I mix OTB, so I like to have the main parts routed to individual faders, particularly the important stuff - main keys, snares, kiks, hats, and lead voices. I may, for example, have a 'room drum kit' designated for a stereo pair, and sub mix that element in the host application. But I'll generally blend that stereo element with individually routed parts for better mix control.
At other times - depending on how time pressed or lazy I feel - I might load two instances of Kontakt or Stylus because I want to experiment with two different approaches and am not ready to do any fancy internal routing from one instance.
But, I'm doing that less and less these days. I'd rather keep things slim and trim.
There it is; more info than you asked for; and far less than I could bore you more with.
CaptDan