Checking repository access through App user installation

I’m building a GitHub App and I need to check if a user can access a given repository through the application. Retrieving the list of user installations (using https://developer.github.com/v3/apps/installations/#list-installations-for-a-user) and then fetching the list of accessible repositories for each of those installations (using https://developer.github.com/v3/apps/installations/#list-repositories-accessible-to-the-user-for-an-installation) works, but it’s obviously far from optimal. Is there a better, more direct, way to check for access?

Thanks!