The first thing you need to do is prioritize your events. Which ones do you want to do best at? You have some conflicting goals here that are going to make it very hard to come up with a good solid training plan. Not to say that you can't do all of these. Just that you're going to have to realize that training for a sprint Du does not help you do well on your first century ride. And training for a century will impair your ability to be fast at the duathlon. You'll get it done, you just won't necessarily do as well as you might hope.
Doing well on a sprint Du requires power work and a lot of higher intensity intervals. A century requires lower effort but sustained endurance. If you train both at the same time, power and speed will tend not to improve as well as you might hope.
Once you've prioritized your races, you can prioritize your training. That makes it a lot easier to figure out what workouts are more expendable than others if you need to cut back your training load.
Also, you need to have periodized program that works in rest weeks. That way you can train more on your build weeks, then rest. This helps to prevent injury and burnout.
If you post you're prioritized race schedule, I'll try to give you some more input. Having said that, I'm super busy with my work as a PT and a multisport coach. So please forgive me if I don't get back to you.
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