Over my last several larger scale audio shoots I've made and then subsequently ignored my input lists in lieu of a different method - tap slating.
Tap slating is what it sounds like. You set all of the mics up about where you want them to go, then run cables and plug them into the recorder. Hit record, and walk around to each mic. Tap the mic and slate.
*tap tap* "that's the schoeps CMC6 MK4 on a shockmount aimed at the exhaust"
*tap tap* "this is a 421 passenger side axle aimed at the tire"
*tap tap* "that's an NT5 in the engine compartment aimed at the heads"
*tap tap* "and this is a CM3 next to the exhaust aiming out behind it"
With everything slated, set levels and you're off.
The beauty of this is that you don't have to stress about which mic is plugged into which channel at the time you're setting up. Just run the all the cables at once, plug them all in and you're good. It also helps on the flexibility/spontaneity side because you don't feel as tied to your preconceived ideas about where you're putting which mic. Spend the moment setting up and listening as opposed to writing stuff down, then tap slate and start rolling.
In post you'll see the tap slates a mile away, and you'll appreciate the better descriptions that you'll dictate to yourself.