H,
For sure. The 80/20 ratio is the optimal intensify balance, but an 85/15 ratio is significantly better than a 75/25 ratio. More easy is better than more hard.
In fact, you can add on time and still maintain the 80/20 ratios, it’s easy! Just add 2 minutes of high intensity for every 10 minutes of running. Even though your 55 minutes run is all scheduled to be easy, if you were to add 30 minutes of running on top, make 6 minutes of that high as intensity. It’s perfectly consistent with the 80/20 plan, as we’ve already calculated the 80/20 ratios for you by each week so anything you add that also is the 80/20 ratios maintains that formula.
David