Can blocks created via the admin UI be cached? I am trying to understand if blocks created using the admin UI can be cached or not? I had a look at the block table in the database and it would appear that the cache value is set to -1 regardless of whether block caching is enabled or not.  So I am assuming that blocks created via the admin UI cannot be cached.  Is that correct?
https://www.drupal.org/project/blockcache_alter might be what you are looking for.