Will that help on the 800 home stretch?
Not specifically, however a good race still benefits from tempo/long run conditioning. My goal was to run at least 40mins and to make it interesting (i.e. beat the dreadmill feeling), so decided on a fartlek format. Tempo pace helps with mental conditioning and basically the last 800 I ran was a cruise effort- hence the need for mental toughness- gotta push all the way!
Yes, I have a definite focus problem on all the gym machines, treadmill, elliptical, bike. 10 minutes without a break is about my limit. Breaking it up various ways really helps!