Are they work boots, dress boots? Doing construction in the winter, and working around concrete and asphalt, I use Obenauf's twice a week. In my case, my work boots are the only thing I wear other than sandals or moccasins, so I have no "dress" shoes to worry about.
There are just too many factors involved to use a "set" procedure.
Leather Preservative Originally Developed for Wild-land Firefighters (obenaufs.com)