Thanks to both Plxxxel and Jongware!
Both of your answers were helpful - I have combined use of both.
Plxxxel - I was aware there was a shortcut (Alt+Left Arrow, Alt+Right Arrow) for incrementing tracking by the amount set in Edit, Preferences, Units & Increments, Kerning & Tracking. What I didn't realize was that Ctrl+Alt+Right Arrow, Ctrl+Alt+Left Arrow increments/decrements that setting by 5 times. So, for my usage, I have set Tracking at 1. Then I use the Crtl+Alt arrow combinations for rougher (5 incr.) spacing and Alt arrow combinations for fine (1 incr.) tuning. That actually is the practical solution for me.
Jongware - Thanks for your scripting solution! Your answer was correct according to what I asked in my original question.
I found it can be more useful if I adapt it to increment additional tracking amounts:
/*
<javascriptresource>
<name>Character Tracking. Increase</name>
<enableinfo>true</enableinfo>
<menu>automate</menu>
<about>Adjust the kerning.</about>
<category>Typography</category>
</javascriptresource>
*/
app.selection[0].tracking = app.selection[0].tracking + 10;
[Similar script for Character Tracking.Decrease.]
So assigning these scripts to keyboard shortcuts like Alt+1, Q, I have:
Alt + arrow = increment by 1
Ctrl+Alt + arrow = increment by 5
Alt 1/Q = increment by 10
Actually, my needs are sufficiently met by just using the built-in Alt and Ctrl+Alt arrow combinations, but thought I would document the simple script alternative in case anyone could make use of it.
I think I have graduated to becoming an amateur.
Thanks again to both of you for your help!