Each project has its own unique character. Therefore, the advertising strategy, methods, and tools for promotion are determined separately for each project. It is extremely rare when an application does not need promotion, this is possible only with unique content or the idea itself. It is cheaper to promote this kind of application than in the case of typical applications, whose counterparts already exist in large numbers.
Google Play and App Store rankings are based on the number of installs in the previous days. As you go through the stages of promotion, the application will be installed, which will certainly lead to an increase in positions in the search results, both in the corresponding category and in the general top.
The higher the app's rankings, the higher the rate of unmotivated installs. This chain is reciprocal and interdependent. Even in the case of a short-term stay (2-3 weeks) in the top 100 Google Play / App Store, all investments in the promotion will be fully paid off.
The main thing to understand is that as soon as you pause the promotion, your mobile application will inevitably lose its top positions, and at some point, it will reach 0 in terms of installations. For the Studio Webmaster team, it doesn't matter if your mobile application is a new project or an old one at the bottom of the search results in the App Store and Google Play. Although the price may well differ since the cost of promoting a mobile application in 90% of cases is calculated individually.