Maintaining 60+ Mobile apps is not an easy job
Over last 5 years, we developed 60+ iOS and Android apps. We are a small indie team. 2 full time developer and designer including me, and sometimes some part time freelancer programmer join us. I personally handle and maintain all the apps in the store, periodical updates, bug fixing etc. But maintaining this number of apps takes time. It needs careful selection of priority.
Just get rid of the crappy stuff and focus on the good stuff.Steve Jobs
I love this saying from Steve Jobs, also there is another similar saying:
Get rid of things and focus on what matters
This is how I maintain my apps. I have a priority list based on downloads and revenue. The apps which download most or which generate good revenue, I give high priority to them and update often. But some of my apps are failed in the market. A tiny number of downloads, so either if it really needs update, I do it in very late or I totally stopped upgrading. If any of my apps are not download further, I remove it from store. It happened for two of my very old apps.
App architecture is also very important for maintenance. An app which follows the standards, have sufficient comment and have updated technology are easy to upgrade. For example, the iOS app which originally written in SWIFT 1 language is easy to upgrade in SWIFT 2. So upgrading apps periodically makes maintenance easy in future.