That's fine in things like ice cream flavours and car paint colours and oil filter brand and choice of carburetor, radio station, and shirt, but not in headlamp aim. For any given headlamp mounted at any given height, there is ONE (and only one) correct aim setting.
I must be doing something right because oncoming vehicles don't flash their lights at me
Don't be so sure. The human visual system is a lousy judge of its own performance, especially under the conditions (called "mesopic vision") of night driving. It is very easy to create situations in which we think/feel we can see a lot better or not as well as we actually can.
By-guess-and-by-gosh methods like yours are just plain not good enough, full stop.
