In Kotlin Multiplatform, a high percentage of shared code is not a success metric by itself. Moving every similar Android and iOS implementation into commonMain can introduce interfaces, expect/actual declarations, and extra layers that make the project harder to change. Before sharing code, the important questions are whether the business rule is genuinely the same, whether it can be tested independently of the platform, and whether the abstraction is actually simpler than two small platform implementations. Domain logic, networking, and data transformations are often strong candidates for sharing. Permissions, navigation, lifecycle behavior, and UI details can be clearer and easier to maintain when they stay platform-specific. The goal of KMP is not to maximize shared code; it is to reduce real duplication without making platform-specific changes more difficult.