The adaptive training advisor will suggest workouts based on tiredness, remaining XSS and perhaps other things.
If you put workouts in the planner the advisor will assume they will be completed and the recommendation is what additional work is required. That part is fine, however, I think the wording can be improved:
Your Training Status is Fresh and have some training still left to complete. You should consider an Endurance workout or activity generating about 1 XSS of overall strain, with less than ◆◆◆◆⬖ difficulty.
In this case I already have a planned activity for the day, and I think the advisor should give me a better advice:
a) Extend the planned (or one of the planned) workouts with 1 XSS
b) Add an additional workout, but then use a reasonable minimum XSS target of 30 XSS or so, or
c) Have a reasonable cutoff of remaining XSS, and call this workout optional (same as you do if remaking XSS was 0)