Named instances and default instances differ in connection strings, ports, SQL Browser discovery, and the operations each one needs.
Naming SQL Server Instances So People Understand Them
Naming SQL Server Instances well clarifies default and named installs, survives growth, and makes later server renames less painful.
Consolidating Small Instances Onto One Server
Consolidating small instances can reduce hardware sprawl when configuration conflicts, peak workloads, licensing, and migration order are checked.
Keeping an Inventory of Every SQL Server You Own
Build an Inventory of Every SQL Server you own, including hidden instances, owners, versions, recovery details, and a process to keep it current.