Do you know or are you guessing? Following plans that push repeatability and not max efforts? The critical power testing methodology (feed it to free GoldenCheetah or Intervals.icu) is pretty good if you do a longer 30+ minute effort along with shorter efforts at say 3-min, 6-min, 12-min, 20-min and one long one. You can reduce that to 3 max / near-max efforts. Or buy WKO and feed it with efforts.