Forget about junk miles. If you are riding at a reasonable pace, and if your heart rate is in the 140s you certainly are, then extensive long steady distance (LSD) riding will do as much for you as intensive training. It takes longer to derive the same benefit, but it has some advantages too: one can recover overnight from extensive moderate efforts whereas a high-intensity intervals session might limit you to a rest day or just a recovery ride the next day.

The main reason people have moved on to shorter "sweet spot" rides at higher heart rates and power outputs is that it means they can get the same adaptive effects while spending less time on the bike. If you have the time to do long rides, that's great. And if they are mixed in with more intensive short efforts while you commute, I'd say that's a pretty effective, varied training programme. The only thing you are probably missing is the eyeballs-out zone 5 work that will give you the neuromuscular adaptations needed for the " jump" at the start of a full-on sprint, but hey - not everyone wants to be Mark Cavendish.