Apple sold $10 billion worth of apps in 2014, continuing app developers stampede into mobile apps. According to Appfigures analysis, that stampede resulted in greater-than-50% growth for both Apple’s App Store and Google Play Store in 2014, in terms of the number of apps. Apps, in other words, are big business.

But that doesn’t mean you should build one.

In conversations with a wide array of businesses, confusion over the value of building an app runs rampant over common sense. The reality is that apps are not always the right answer. As with so many things in life, “it depends” is the correct response to “Should I build an app for that?”

But first, the jaw-dropping numbers

Based on the sheer number of apps in the different app stores, most companies seem to think the answer is “Yes.” Appfigures tallies up the total number of apps and finds that we’re now awash in nearly three million apps:

As impressive as this is, it’s far more impressive that the app market keeps growing at such a torrid pace, given its size:

Each of the app stores generated at least 50% growth. That’s amazing.

Equally impressive, while Google now has more developers writing apps for Android (388,000) than Apple (282,000) and Amazon (48,000) combined, it’s far more interesting to note that at these growth rates, we should see the mobile app developer population swell to one million developers in 2015.

Which is not to say you should join them.

The dark side of mobile apps

After all, the odds of anyone using your app are pretty slim. Everyone likes to cite the factoid that mobile users spend 86% of their time in apps, not the web. It’s a true statement.

It’s also irrelevant.

Because, let’s face it: they’re not spending time in your app. For any given individual, nearly 70% of the time they spend in apps is confined to their three most frequently used apps, according to Flurry data.

And, hey! You just might break into that top three, but only if you’re a game (32% of time spent in apps), Facebook (17%), or social messaging (10%). That leaves 41% of the market to play for, unless you start subtracting Twitter (2%), utilities (8%), and YouTube (4%), in which case you’re left with roughly a quarter of a user’s potential app time, spread across an average of 26.8 apps people use on a monthly basis (according to Nielsen data).

Still want to try? Of course you do!

Just keep in mind that building an app is the easy part. Next, you have to acquire users — according to Fiksu, that will run you $1.46 (iOS) to $1.15 (Android) per app download. I’ve heard of some companies paying upwards of $70 per app download.

All of which sounds less appealing when you consider that roughly 52% of apps lose half of their peak users after just three months, according to Flurry data. Games, despite being the biggest consumer of user time, struggle the most to retain users: 50% of gaming apps lose 50% of their peak monthly active users within two months.

The cost of retaining users, ironically, is even more expensive than acquiring them in the first place, according to Fiksu data: $2.16 per user.

None of which makes sense if your business doesn’t really have a reason to build an app in the first place.

What, no app?!?

Yes, that’s right. Not every company (or industry) should build an app.

Take the travel industry, for example.

As Phocuswright points out, road warriors aside, most people travel just two or three times per year, and they aren’t going to install an app to accommodate this sporadic use. Even those that use an app also use the mobile web. This fact shines through in a TripAdvisor example:

“TripAdvisor is one of the most popular travel brands in the world. A little over 30% of the mobile study participants used the brand on their smartphones during the month Phocuswright collected the data. But while many (13%) used the app, even more (18%) visited TripAdvisor’s mobile website. Even the app users visited the mobile website, too. Overall, only 38% of TripAdvisor smartphone users were ‘app only.'”

As the study concludes, “the majority of travelers want quick access to travel information without having to download an app.” To reach these travelers, a strong mobile web presence is needed even more than a robust app (though if you’re an airline, an app is critical, because travelers will also use it for boarding passes, to track flight status, etc.).

Or maybe you’re a book publisher. Or a law firm. Or any number of types of organizations for which an app may not help you more deeply engage with your customers.

This is NOT to suggest you should dump your plans to build the world’s greatest app. It is, rather, a suggestion that companies should carefully consider what their goals are for mobile. “Build an app” is not a strategy, though it’s what many have opted to do in their haste to DO SOMETHING RIGHT NOW.

Sometimes, you just need a great web presence, optimized for mobile. Sometimes, you need a loyalty card or discount card or something else that can be left in a user’s Passbook or Wallet.

And sometimes, you just need to engage with a user through notifications. To date, that has required that your app reside on a user’s device — but that’s changing. Indeed, as Paul Adams writes,

“In a world where notifications are full experiences in and of themselves, the screen of app icons makes less and less sense. Apps as destinations makes less and less sense. Why open the Facebook app when you can get the content as a notification and take action — like something, comment on something — right there at the notification or OS level. I really believe screens of apps won’t exist in a few years, other than buried deep in the device UI as a secondary navigation.”

We’re not there yet, and we may never get to the exact experience Adams describes. But we’re also no longer living in a world where the answer to every question can or should be, “There’s an app for that.” So, before you build, consider what you’re trying to accomplish, and build the right tool for the job.