mcjaco: Same here. In fact, I don't even own a scale ruler, in spite of being in N scale for almost 50 years. I convert everything to scale inches, then use a stainless steel ruler marked in 64ths. It's good to 2.5 scale inches, which is better than the scale rulers available when I was starting.
If I really need scale feet, I have an engineer's ruler, 12 inch plastic, marked on 10ths, 20th, 30ths, 40ths, 50ths, and 60ths. The 50ths will also measure Evergreen styrene. so it does double duty, on the rare occasion I find a misplaced strip.
For plastic or metal strip and rod, 0.01 inch equals 1.6 scale inches, which is also easy to work with.
I use relatively few drill bit sizes, so keeping them separate isn't hard.
Did I mention that I'm cheap?