This feature send like a good idea What is the goal of this suggested workouts? Is this to maintain your current fitness or generally improve your performance for a certain distance?
Based on observations on my side it helps keeping optimal physical load and also properly balanced.
The feature documentation is a bit vague: "These workouts are designed to help you maintain or improve your current fitness level"
https://support.garmin.com/en-US/?faq=oYknGZ910l1pfBNzkDHX6A
What I'm seeing I would probably say that doing what they suggest would probably be detraining.
I think is a good idea and by the moment their proposal has been similar to my program
More information can be found here - www.garmin.com/.../