Not cycling, and not VO2 but I know this to be true. My best 1600 meter time in high school (1981) proves it so. 4:36, jr varsity second place district meet. Then in Varsity district only the top 16 athletes in each event were allowed to compete. My time and the time of the winner of my race were in that top 16 but since they were in the jr varsity district meet they did not count. How I did it was to use mental toughness and a burning desire to do the best I could. My previous best time that season was in the mid 4:40's at best. I dominated the junior varsity mile that season and had confidence in my speed and endurance. I pushed myself in ways that surprised and still surprises to this day my coach. When folks work past their fears and self doubts amazing results occur. Most of us never reach that point. I am not sure I have done so more than once. Jens Voigt once said "bike racing is all about who can suffer the most!" His ability to suffer made him a star.

Training for VO2 Max efforts should increase your ability to do so. Accuracy of any numbers in a tracker might not be there but I think it is fair to conclude that if you are using an estimator on a regular basis the trends displayed likely are correct and add value.