This is my first post in the Over 35 forum (I'm 34 but I guess that's close enough). I haven't done Dan John's one lift a day actual program but my own training for the last 2 years has centred around something quite similar. It consists of the following:
Monday: OHP and chin-ups (variations, especially sternum chins)
Wednesday: weighted dips and Zercher squats
Saturday: deadlifts and chin-ups
No other lifts, that's it. Reps for all movements range from 1-5, high volume per movement (approx 25-30 reps per lift). No other program has given me the results (strength and physique) that this one has in my 17 years of strength training. I think a lot of the time people are afraid of stripping down their training to something this basic but as Dan John says, something magical happens when you can go into the gym and focus all your intensity on hitting one (or in my case 2) movements and that's it.
OP: if you hit this program hard with a ton of intensity and make sure your recovery is dialled in, I GUARANTEE you will make amazing gains. I can't wait to see your numbers on your lifts skyrocket!