I find constant zone 2 hard and generally somewhat boring. I shoot for the talk test and try to set a level of effort just where speech is starting to be affected (VT1). What I would really like is a team car following me with a lactate meter and I would stop at prescribed times and test blood lactate to adjust power. I thought about a buying a lactate meter and performing loops around a local island with my car parked on the route and I would stop and perform a lactate blood test and then adjust my power. Pretty geeky and it seemed like a pain in the ass.

I find constant power with no stopping at zone 2 very hard. However, I think is supports the other energy producing systems that require different muscle fibers that generate more lactate. Slow twitch muscle fibers with well developed mitochondria (constant power efforts) will burn the lactate produced when riding tempo power and higher.

I can only imagine what it is like for the UCI world tour and continental pros that ride hours at constant power with cars following them with lactate meters making sure they are at the most efficient lactate level - brutal.

I will take intervals any day over long constant zone 2 riding.

What about noodling around at an easy power with stop signs and traffic lights and taking short breaks on or off the bike? Why not? I will call that sort of junky but not insignificant.

IMO, planning any riding is about the goal. If the goal is hard, such as back to back to back days in the mountains riding with hitters, then I need a lot of hours on the bike at zone 2 with supporting, VO2, threshold and tempo riding with a lot of climbing. And some of the riding can be noodling around at low z2/z1.