Efficiency of thrust reverser depends on too many factors to simply list in a document or with an easy equation.
Regarding OP statement in regards cycling of auto brakes there is some truth in this...
Essentially initially the auto rake will ramp up to a preset value, after a time delay which depends on the setting it will 5en increase brake pressure to achieve the commanded auto brake deceleration rate. It continues to monitor the rate and when the rate is achieved it will reduce brake pressure to maintain the rate commanded, if the rate achieved exceeds the commanded rate the brakes do not go back on until the rate decreases below the commanded rate, this causes the cycling as described.
With autobrake 1or 2 selected and the application of 2nd detent reverse thrust the autobrake will not need to apply brake pressure for the majority of the landing roll after the initial ramp up and application, as the reverse thrust and other stooping devices exceed the rate reduction commanded. With an idle reverse landing the continue to apply brake pressure throughout the landing roll at all times.
Hence when a landing with autobrake 1or 2 is made and reverse is still applied when disconnecting the autobrake a shock can be felt as the brakes are manually overridden, as they are not doing anything until the 1100psi is applied to override them. Stowing the reverses to idle and then overriding the brakes ensures a smooth transition as the brakes will be required to exceed 1100 psi by design thus foot brake pressure override is smooth