...patch cables go from input to output hence an optimised system should ideally have the same number of these, no matter which modules are included...
-- Dan_ogq

I disagree. for me an optimized system is defined by other aspects than than the relation of I/O's
- most important: can i achieve the audible results that i want?
- is it ergonomic or is there room to optimise by rearranging some modules?
- is it performable the way that i want?
- is it easy to get every module perfectly in sync without struggling with missing clock ticks?
- do i have enough headroom with my power supplies?
- is my lightning ok regardless where my rack is located?
- is there any audible result i want to achieve but not possible with modules i have?
- is it easy for me to find/grab the right patch cables?
- etc.

those are a few of my thoughts to optimize my personal rack...

-- modular01

just one more point to tick, i don't see why one should exclude or be considered more important than the other, after all, my extra point is just about adding more automations.

Conversely, I notice that my Tetrapad has 8 outputs... and no inputs.
No inputs? Nightmare! I have become the module and my fingers are the cables...

-- Sweelinck