I’ve set each days workout to start at 09:00 rather than what the system recommends however when I want to choose a workout and look at the availability it still shows the recommended time rather than the time I have stipulated
If you enable Automatically Schedule under Planner Settings your custom Start Time will apply to workouts added to the Planner after midnight each day.
For example, if I set Custom, 9:00am, 1-1/2 hours on Monday (all or a selected date), that is what I will get on that day.
I suppose the same logic should apply when adding workouts if Automatic isn’t enabled but you’ve configured Start Time by day.