What is the best practice related to using the Default Update Set for moving customizations between instances?

Merging Default update sets can combine untracked changes, making it harder to manage and deploy specific customizations.

Update sets are typically committed to another instance or stored in source control, not submitted to an "application repository" in the context of standard update set movement.

The Default Update Set automatically captures all changes made on an instance if no other update set is selected, making it prone to containing unrelated and untracked changes. For controlled and organized deployments, it's best practice to create and use named update sets that capture only specific, related customizations.

There is no specific best practice to limit the Default Update Set to 20 records; the general recommendation is to avoid using it for migration altogether.