A KPI tree breaks revenue into users and revenue per user, then further into installs, retention, payer conversion, ARPPU, impressions and eCPM. It helps teams see which lever has the most leverage and which metrics actually depend on each other.
Real products are graphs rather than trees: the same driver (such as retention) feeds several branches, and changes in one branch affect others. Treat the tree as a map for questions, not a guarantee of independent levers.