Caching for each subsystem, such as catalogs and orders, is configured in their respective configuration files. For catalogs for example, see ecf.catalog.config in the configs folder of the site.
The collectionTimeout responds to an entry array, and "entry" responds to a single entry. What is actually cached is the CatalogEntryDto and, because the Entry object is created from the Data Transfer Object (DTO), you cache the DTO.
The following is found in Commerce caching documentation: https://world.episerver.com/documentation/Items/Developers-Guide/Episerver-Commerce/9/Caching/Caching/
So, the fact that it's the CatalogEntryDto that is cached, does that mean that this cache is not relevant if you are only accessing commerce objects through ReferenceConverter and IContentLoader? Or is this cache used when browsing the Commerce Ui?