What changes, as it waters the same number of minutes per zone as you've had hot and cool days, is the frequency of watering. The hot days cause waterings to happen more frequently, the cool days cause watering to happen less frequently.
The end result is a variable amount of water is being put down based on evapotranspiration for the day. That's what your Toro was doing, but in an opposite manner. Watering every Wednesday, no matter what, but putting down a variable mount of water.
Where I find the Iro is still deficient is it's adjustment of evapotranspiration as a function of daytime temperature (it's currently as linear and proportional function) and month of the years (not paid attention to). If this advanced calculation were to be performed, then people like me would not have a season where the right amount is going down for most of the summer, but, during the real hot days, not enough water is applied.