The bro split trains each muscle group once per week with maximal session volume. Frequency-per-muscle is lower than PPL or upper/lower (1x vs 2x per week), but session volume is higher — typically 15-25 working sets for the target muscle.
Modern hypertrophy research generally favors higher frequency (2x/week) for most intermediate lifters, but advanced lifters who can productively absorb very high single-session volume can still grow on a body-part split. The key is hitting every set close to failure, since you only get one weekly chance per muscle to drive stimulus.
On MuscleBuddy this program runs with double progression on compounds and RPE-based progression on isolation. Compounds anchor each day at RPE 8; isolation pushes to RPE 9. The engine tracks how many reps you hit per set and advances the load when the top of the rep range is reached.
Recovery is the bottleneck. With a once-weekly frequency you have six days between sessions for a muscle to fully recover, but the volume per session is so high that systemic fatigue (sleep quality, joint stress) is what limits progress. A four-on / one-deload mesocycle structure is non-negotiable.