Going back to very low intensity for hours upon hours is a way of training reserved for those who have the luxury of unlimited hours to train. For most time starved, working athletes reducing your training intensity completely for the winter months will leave you in worse shape than when you started.
Jim Rutberg makes a great point here in that most athletes who've been training for a number of years have reached a ceiling in terms of the number of hours per week they can train. So where do you go from there? Progressively increasing your training load, improving the quality and focus of your workouts over a year long periodised training program will ultimately lead to better results.
Doing Less With More Doesn’t Work. As an endurance athlete you have already habituated to a certain volume of weekly training hours, likely because that’s all you have available. Training the same number of weekly hours (because you don’t have the time to add more) at lower intensities produces a lower total workload than you have already adapted to. As a result, it won’t stress your aerobic system enough to stimulate a positive adaptation.