Interesting results yesterday as I haven’t tried riding two activities in one day on a XFAI plan before. I hadn’t planned to do that but here’s what happened.
While playing around with an expired test account (no XFAI Beta option) I managed to select the default workout (Let the Sparks Fly) which didn’t match my XFAI HIT goal for the day.
I was also testing EBC iOS and the Session Player on an iPad which I do every now and then. 
I realized a few intervals in I had the wrong workout, but decided to complete it since it was a HIT workout with some relevance to the goal. When I finished and uploaded, I got a red sticker since I was short on low, high, and peak scores for the day.
To my surprise the recommended list now displayed fill-the-gap workouts which were short ones that I never do. I selected the second entry 13 Minute Workout which looked feasible at first glance.
However, I psyched myself out during the first interval when I looked up under pain and saw I was only halfway through. Bailed on that one but got through the remaining intervals without incident.
As a result, I got what I needed to go green. 
There is some leeway built into the scoring .
Plus –
Equaled –
At that point the recommended list went into Active Recovery mode as expected.
Nice!!!