Yeah, while in a plan I generally keep an eye out for things like reduced RPE for similar workouts, or I may struggle to finish a 15 min interval one week and then push it out to 20 min a couple weeks later. Things like that will start to happen and be noticeable without pushing all-out efforts. The all-out efforts also cause much more fatigue than they give you in training benefits so they may not be the best thing in the long run even though it is a nice mental boost to see that.