Yeah, sort of doing that....

It automatically adjusts incline.... speed is up to me... so yeah... every so often I'll kick it up to a little over 4mph, (all I can do without breaking into a jog). I also start very slowly... around 2.4 mph to warm up but I don't count that as part of my workout.

You're dead right, Frank. Back when I was a workout demon I discovered that I couldn't really run a fast ONE mile... even though I could run all day. That bothered me BUT... I never trained for running a fast mile I trained for backpacking and being able to go from morning til night. Still... call it 'pride', I guess... for a couple of years I was dissatisfied with myself because I couldn't run a fast mile.. THUS:

I read up, the experts, and did almost exactly what you're recommending. I ran my regular run but I added some interval sprints... all out for 100yds, then walk 100, then full out again for another 100yds... and I'd do that for a mile, sometimes a mile and a half.... almost immediately my mile time came down, A LOT.

That lasted for about 2 years... and I quit doing it. Reason: I never really cared how fast I could run a mile... I was a backpacker... so I kept my heartbeat up and steady... and I couldn't run FAST... but I could run from sunup to sundown. - JamesJM

P.S. Those days are far behind me.