Keep in mind that posting time can be up to several weeks. Let's say you have developed and tested an application, called all the bloggers or the media and said: "I have a new application, come to the press conference." You send it to the AppStore and have to wait seven working days in Russia. In this case, Google Play is a paradise for live updates, where publishing takes several hours.
Fragmentation of the operating system. If you are developing applications for Android, consider fragmentation and the existence of a whole zoo of devices. This affects the development time at all stages: design, design, development, and especially testing.
It is impossible to communicate with users in the store. For example, a user writes that he does not receive messages in ICQ. He is dissatisfied and expresses himself very colorfully, but not very informatively. We have no way to contact him and find out more about the problem. All we can do is get into the monitoring and see if we have messages. Maybe it was blocked by antispam.
Now some stores are acquiring an admin panel in which you can ask questions to the user, find out his contact details, see in which countries your application is downloaded, but so far the situation has not improved much. It is worth noting that Google Play continues to add this feature to some developers, for example, our company is available.
Time for testing. There are several ways to test an application. You can have testers on staff - with test cases, test plans, which they must pass. In addition, there is a service for testing - you pay for the bugs you find. You upload an application, 20,000 people test it. There are, of course, pros and cons to this approach.
Personnel in the mobile industry is everything. Good mobile developers are hard to find even for large companies such as Mail.Ru Group, Yandex or Google. That's why we work with interns - because sometimes it's easier to take a smart student and train him.