This must make Coach Jeff sad.
So I started the 5K run-walk-run training plan, but found that the workout for Run Walk Run only contained a Run step with a Duration Type of Distance 1m. So I guess I'm expected to just time this on my own and keep looking at my watch?
So I guess maybe Garmin Connect doesn't have the ability to configure a workout to do repeats of two different steps (Run and Walk) until some other duration type is met, like distance 1m, and can only specify a number of repetitions.
So I tried using a Run/Walk alert which is configured within the Run activity only to find that this alert type (or perhaps all alerts?) are disabled for activities during workouts.
Also see here (other thread) for more detail.
I'm posting this here just because I'm not sure what can be done to work around this difficulty within the Garmin Connect app, and what's going to require both firmware improvements and corresponding improvements to the Garmin Connect app.