How far away is your Ironman? As you complete sessions and progressive overload gets applied, you should see the durations increase. Plan is adaptive, nothing in the future is fixed regards volume.
This exactly - the future workouts are based on your current fitness and will start to adapt as you ramp up each week. I also found it confusing to not know what to expect down the road when spying on future weeks LOL, but over time it DOES adapt and increase plenty!