Case Structure Builder
Pick a template, then make it yours. Rename branches, add sub-drivers, cut what doesn't earn its place.
root
bucket
subdriver
subdriver
subdriver
bucket
subdriver
subdriver
subdriver
bucket
subdriver
subdriver
bucket
subdriver
subdriver
subdriver
MECE check
4 top-level branches, 11 leaves. Three to five branches is the range an interviewer can follow.
A structure you built yourself is worth more than a template. Keep going with the free resources and the Bain online assessment.