It's a similar situation with Chrome extensions. Extension reviews are generally pretty quick (an hour or so), but every once in a while you get hit with a longer one (days+).

In this type of environment, you need to ensure every release is as rock-solid as possible. For our extension, we have beta extension with a sub-group of opted-in users that we test on for a week or so before doing a production release. Then we roll out the extension to production incrementally starting with 1% of users and slowly ramping that up to 100% (it seems Android has a similar staged rollout feature).