Do you Instrument or do you Function?

A workflow question to the forum: do you organize your racks by function or as an instrument? I used to organize my rack according to instrument workflow, for example left to right through a subtractive chain VCO to VCA. Because of the sheer number of modules I now have, and my experimenting with folding signals back and forwards and sideways, the linearity doesn't seem to matter as much.

I'm building a new studio and I will be putting things into dedicated racks instead of a bunch of mismatched cases—mobility isn't an issue. I am leaning toward lumping all the VCOs in one section, all the VCFs and another and then the utilities and such in a third and so on. I realize that this will depend on how many modules and/or cases one has (I have a lot), and the "whatever works for you, man" thing, but I'm interested in others' thoughts on workflow arrangements.

So, what do you do and why? Thanks and Happy Noodling!

EDITED Yesterday, 20:39

I have adjusted and refined my setup many times over the past five years. I've bought, sold, re-bought, and rearranged countless modules and have finally (mostly) settled on what works for me. The general idea is aligned with the signal flow of a traditional fixed-architecture synth. After so much experimentation, I know how I usually use each module and I have arranged them to have the shortest cable runs possible. I like to constantly tweak knobs, so keeping cables as short and out of the way as possible is important for me. I try to have my signal flow going from left to right and top to bottom so I can avoid too many criss-crossing cables, which is visually important for me so I can remember where everything is going. I'm getting too old to remember how I've routed everything otherwise. Haha
Good luck and have fun!

After seeing this video of Monotrail Tech Talk, I've settled to a "function" organization.

Basically he divides systems in four main categories :
1) The MonoSynth
2) The Sonic Exploration Lab
3) The Performance System
4) The Dedicated Tool

It helped me a lot to think about my systems this way.

Within a case, I follow the signal flow from left to right, with sequencers in the middle.