ImportancePhysicians spend the plurality of active electronic health record (EHR) time on documentation. Excessive documentation limits time spent with patients and is associated with burnout. Organizations need effective strategies to reduce physician documentation burden; however, evidence on team-based documentation (eg, medical scribes) has been limited to small, single-institution studies lacking rigorous estimates of how documentation support changes EHR time and visit volume.ObjectivesTo analyze how EHR documentation time and visit volume change following the adoption of team-based documentation approaches.Design, Setting, and ParticipantsThis national longitudinal cohort study analyzed physician-week EHR metadata from September 2020 through April 2021. A 2-way fixed-effects difference-in-differences regression approach was used to analyze changes in the main outcomes after team-based documentation support adoption. Event study regression models were used to examine variation in changes over time and stratified models to analyze the moderating role of support intensity. The sample included US ambulatory physicians using the EHR. Data were analyzed between October 2022 and September 2023.ExposureTeam-based documentation support, defined as new onset and consistent use of coauthored documentation with another clinical team member.Main Outcomes and MeasuresThe main outcomes included weekly visit volume, EHR documentation time, total EHR time, and EHR time outside clinic hours.ResultsOf 18 265 physicians, 1024 physicians adopted team-based documentation support, with 17 241 comparison physicians who did not adopt such support. The sample included 57.2% primary care physicians, 31.6% medical specialists, and 11.2% surgical specialists; 40.0% practiced in academic settings and 18.4% in outpatient safety-net settings. For adopter physicians, visit volume increased by 6.0% (2.5 visits/wk [95% CI, 1.9-3.0]; P < .001), and documentation time decreased by 9.1% (23.3 min/wk [95% CI, −30.3 to −16.2]; P < .001). Following a 20-week postadoption learning period, visits per week increased by 10.8% and documentation time decreased by 16.2%. Only high-intensity adopters (>40% of note text authored by others) realized reductions in documentation time, both for the full postadoption period (−53.9 min/wk [95% CI, −65.3 to −42.4]; 21.0% decrease; P < .001) and following the learning period (−72.2 min/wk; 28.1% decrease). Low adopters saw no meaningful change in EHR time but realized a similar increase in visit volume.Conclusions and RelevanceIn this national longitudinal cohort study, physicians who adopted team-based documentation experienced increased visit volume and reduced documentation and EHR time, especially after a learning period.