If you try what you suggest you’ll see it only works once.
In your example, you can see Tallac is next. So yes, you can click and select it and do the workout.
What happens next is that a new Tallac gets inserted into your calendar on the day you did it and the original Tallac part of your workout plan remains unchecked as if you never did it.
So next time around the trick of scrolling up won’t work anymore, as the first unchecked workout is still Tallac. You’ll have to remember that you already did it and you should be doing Juneau-1. The further you go down the list the messier it gets.
Here’s a screenshot to illustrate. Yesterday (12/4) I did Tunemah by using your technique of scrolling back and selecting it from 12/1. But Tunemah didn’t get checked off, instead it added a separate Tunemah, disconnected from any training plan.
So looking at this now, how am I supposed to know what’s next? The app is actually telling me today 12/5 I should do Carter. But that’s nonsensical and wrong, because after Tunemah comes Leavitt+2. The more I work through the plan, the messier and messier this will get and it becomes impossible to know what’s next.