When to use gosu enhancements?

I've seen the usage of gosu enhancements a lot within Guidewire application. However, it seems to me it is being overused. Like the following examples:

• An entity querying another entity (i.e. looks to me an entity modeling problem).
• An entity calling a webservice (i.e. its beyond the purpose of the entity).

Are there any recommended use cases when to use enhancements?

Yes, Enhancements are supposed to be used only for straight forward calculations which the business does not want to store in Database tables. Instead of using the enhancements, I think its better to have a helper Gosu class Where we shall execute the complex queries and some logical calculations.