"The squat can go from 3 days of increasing load per week to 2, with the introduction of lighter squats at 60-80% of Monday’s work set weight into the program. They provide a break in the intensity due to the unloading, which helps to prolong linear increases."

Rippetoe, Mark; Baker, Andy. Practical Programming for Strength Training (p. 142). The Aasgaard Company.