In a Spring application, how often do you actually write GoF creational patterns by hand, and why?

Rarely, because the container is the factory and the singleton manager: @Component gives you managed-singleton scope, @Bean methods are factory methods, @Profile/@Conditional plus @Qualifier select families like an abstract factory, and @Scope('prototype') gives fresh instances.

You still write an explicit factory when you must build objects from runtime data the container can't know in advance — that's where ObjectProvider<T> or a small FactoryBean earns its place. The senior point is knowing the patterns so you can recognize what the container does for you and spot the gap it doesn't cover.