Autobahn, Gateway, and Hallet are all under 2miles length. Although Gateway has a pretty good 'straight' to use NOS on; and Autobahn sets the field. There's some benefit to getting good scores early, while more cars are running, so bigger gaps reward bigger points spreads.
A 5# bottle would get us through a Low ET run, but I need to make sure to take the car to a drag shakedown so we have an idea of what bracket time to put in.
High Plains is 2.55miles, and at altitude... so trying to run a 15# bottle to empty over am/pm sessions probably makes good use of a bottle. Heck, maybe I should get some 75hp jets to swap in for there, so I'm at "altitude corrected hp levels" while everyone else is wheezing.
Cresson's afternoon session is over 3miles, with several long straights... so, good for a 10# bottle... although I've got to watch some video and do some math.
That leaves NOLA and NCM. I've got 13-14 laps driving, and ~3laps sighting at NCM (got most of a timed session in when the Shogun spun into the railing in 2016)... so, I could probably stay "ahead" of people that haven't been there. Then again, it's over 3miles with a couple long straights, one out of a 2nd gear corner, that would benefit the use of a bottle.
So, it looks like I could probably get away with 4 15# bottles, or maybe 3 15's and a 5 or 10... depending on what I can scrounge up, without relying on refills.
It hasn't been used much of late, but NOS was semi-prevalent at OLoA in the early 2000's. And it makes some sense... power when you need it (at the track), no power/wear when you're just burning the miles (transits). I reckon an electric-powered supercharger could/would make a lot of sense at OneLap for the same reasons... one of these days, I'll cobble a system together and try that theory out