Using adenoma detection rate (ADR) and proposed surrogate quality metrics, this research aims to ascertain the significance of the day of the week and its contribution to endoscopist performance. About half to 2/3rd of all interval colorectal cancers are caused by adenomas, although about 25% of them are overlooked during standard screening colonoscopies. All adult patients who had a screening colonoscopy performed as an outpatient between January 2015 and April 2020 were considered for inclusion. Each day of the work week’s worth of ADR measurements and proposed quality indicators were analyzed. Secondary outcomes were percentages of patients with good or excellent bowel preparation, trainee fellow participation, performance quartiles of individual endoscopists, and demographic information. To identify potential ADR predictors, a generalized linear mixed model was applied. The study contained data from 1,884 different kinds of screenings. Friday’s ADR was 35.6%, which was much lower than any other day of the week (P<0.001). There were significant differences in ADR between each day of the week and Friday. In addition to being a male (95% CI: 1.12-1.65, P=0.002), having a decent rather than excellent bowel preparation (95% CI: 1.22-2.28, P=0.001), and having a shorter colonoscopy withdrawal time (CWT) (95% CI: 1.02-1.03, P<0.001) were all observed to increase the risk of ADR. Except for CWT (r=0.28, P=0.379), all proposed quality measures were significantly linked with ADR (r>0.811, P≤0.001). According to the numbers, endoscopists tend to do worse on Fridays than they do on any other day of the week. While there is a strong relationship between ADR and several of the proposed quality criteria, CWT may provide some extra insight.