What effort durations? Like @tshortt stated at those durations just use any power duration curve (Strava, TP, TR, GC, WKO, etc) provided you are doing some hard workouts and weekly drop and/or group rides. The local people I see practice racing on Strava are feeding longer efforts, more in the 40+ minute range. It seems straightforward to fill up the power curve with good data below 50-90 minutes by just doing weekly drop rides.