Having to clear the cache that way is not a normal activity. I only suggested it to make sure there was nothing wrong with your downloaded assets.
Assets are meant to help you avoid having to use configuration management to deploy the necessary bits for your various checks and handlers. The power of assets really shines when dealing with ephemeral instances and/or containers. Since checks are subscription based, only the bits for them are downloaded when appropriate. However, if you prefer on your longer lived entities to have CM deploy your checks, using assets is not required.
As for testing assets on the command line outside of Sensu, you should check out this post.