who did a detailed analysis in 1933 to revealed that earlier restorers had " acted with a great deal of restraint " ?
According to critics , the inherent problem with this approach is that it relied heavily upon an assumption that Michelangelo only painted " buon fresco " , that he was always satisfied with the result at the end of the day , and that in four and a half years spent on the ceiling , he stuck exclusively to one approach , and never made small alterations or added details .