Kevin, if you're using flextrack, don't paint it before installing it, as shiny areas will be exposed as the track is flexed. This will occur even if you're installing it as a straight section.
Twenty minutes isn't bad for your first try. You'll get quicker with practice, and you don't have to do them all at one session. I usually painted turnouts until I got tired of doing so, then switched to some track with no turnouts. This broke up the work and that straight track goes so quickly that you'll always feel like you accomplished a lot.
It's your railroad, but you might want to think about using a different colour, at least around the turnouts. Most prototype turnouts, especially the point areas, are kept well-lubricated, as this makes it much easier for a switchman to throw the switch. Often, the tops of the ties over which the points moved were greased, too, and this got carried all over the place, giving everything a darker hue.
Wayne