Is an app really needed?
The measure is frequency. If a user opens you once a month, the app is an icon taking up space that gets deleted in the first clear-out. Opened a few times a week, it earns its place.
The second measure is whether the device itself is needed. Scanning with the camera, assigning work by location, alerting by notification or holding files offline — at some point the browser stops being enough.
What does a responsive site solve?
It removes every barrier in front of access. No install, no update, no store review; anyone who taps a link is inside. It is also the only way to be found in search.
For corporate sites, e-commerce and occasional application flows the answer is almost always this. An app does not do those jobs better — it just adds a download step in front of them.
What is an app’s invisible cost?
The build is half the job. The other half comes after: two store release processes, keeping up with operating system updates, and users stranded on old versions.
On the web, you fix a bug and everyone sees the fix. In an app the new version passes store review and then waits for the user to update; those who never do stay on the old version for months.
Should you have both?
For most companies that is the right answer: the site is the door open to everyone, the app is for the frequent user. What matters is that they are not two separate systems.
The right arrangement: one backend, one set of data, both reading from the same source. An app keeping its own database means two versions of the truth.