Buying is often the fastest route to a capable system. Custom software becomes responsible when available products create material compromise in work the organisation considers important.
Distinctive workflows
If the organisation creates value through a process that standard software cannot represent without constant workarounds, custom engineering may reduce operational friction.
Integration and control
Ownership can matter where critical data, security boundaries or external systems require an architecture that a product cannot offer.
Calculate lifecycle cost honestly
Custom systems require product ownership, maintenance, assurance and evolution. The decision should include those responsibilities, not only the cost of first delivery.
Build the smallest coherent system
A strong custom product does not recreate every commodity capability. It focuses engineering on the distinctive part and integrates reliable services elsewhere.