I am about 7 weeks into AT. Doing low volume for full distance IM. I have done 100% of my workouts and achieved the intensity goals of each workout. I known that AT would adapt downward if I failed a TR bike workout or missed a run or swim workout. But, If I am nailing the workouts week after week, does AT adapt into harder workouts?
Yes, AT will increase the workout if you successfully complete workouts, taking into account your rating (e.g., easy, moderate, etc.).
As your PLs increase, AT might pick a slightly longer workout (e.g., your plan nominally has a 1 hour workout, but AT adaption suggest a 1:15 workout), but my understanding is that this additional time is at max 15 minutes.