"Mobile-first” has been the warcry of web designers everywhere for the past four years. At the point you're probably sick of hearing every designer under the sun stressing the importance of making sure your website is optimized for mobile before all other concerns. I feel you. 

Of course, they're not without good reasons for their enthusiasm. In the past few years, mobile-search has caught up and even outpaced desktop activity, and that's a trend that's showing no signs of slowing down. The number of mobile users out there, and the number of hours people spend on their mobile devices every month, just keep climbing with no ceiling in sight. Make no mistake – mobile is important.

But, (and you knew a "but” was coming) in the rush to optimize, design, and make all things revolve around mobile, some designers have lost touch with how different users approach different sites. While it's true that nothing beat mobile as a first-contact point for users, there are still many things users would rather do on desktop than anywhere else. Designing with a crazed fixation on mobile-first (which let's be honest, might as well just be called "mobile-only”) as the top priority can risk losing those users.

Too many designers are overly zealous in their quest for mobile efficiency, to the exclusion of practicality. You can't just design according to some dogma or newly-decreed it's also important to understand how visitors actually behave and use your site. More specifically, it's important to know who your most valuable visitors are and how they use your site.

The purpose of any site is to increase visibility and drive conversions. You want your visitors to find you, be engaged by your website, find what they're looking for, and ultimately purchase your product or service. While it's true that mobile might be the king of discovery on average today, that doesn't mean it's the king of conversions. It also doesn't necessarily mean it is the optimal platform for your particular business.

For some, mobile makes a ton of sense. Restaurants, transportation services, concerts, shows, events - anything that people are going to want to be able to access and buy while on-the-go should definitely be focused around a mobile-first design. This means focusing on the mobile experience by designing for speed, light-weight content, and simple, easily accessible navigation options.

But what about other products? If you sell a complicated service, or an expensive, premium product, are your customers likely to be picking it up while in-line at the grocery store? No. They have different priorities and require and different user experience to convince them to convert.

Your product or service might not be the kind of thing people need to be able to buy while on-the-go. Your user experience might be better served by providing a rich wealth of content that visitors can pour over and analyze. Detailed specifications or technical information that users would want to sit down with and compare against other similar products before making a final determination, not thumb through while walking across a parking lot. A site optimized for this kind of content and experience is going to have to look a lot different from a site based on a mobile-first philosophy.

Being mobile-friendly is important. Even if your customers are the type who are going to want to sit down and spend some time with your site and product in detail before making a purchase, you're still going to want your site to be accessible and usable on a mobile device. 

This is where responsive design comes in. It takes the desktop site and makes it work as fluidly as possible on a mobile device without changing the content or character of the site at all. 

Conversely, mobile-first design is built from the ground up to cater to a mobile experience. This means you have a fast, feather-light site that's great for swiping through on your phone – but seems surprisingly empty and featureless if you ever bring it up on desktop.

Responsive design gives you options. It lets you scale your site and features for the device your visitor is using. Mobile-first wears it's priorities on its sleeve. While it can be a great option for sites that do the majority of their business on 4-5 inch screens, it doesn't leave you much room to grow for a more robust desktop experience.

Don't forget where your real value lies. Being mobile-friendly is not the same as a mobile-first philosophy and it might make more sense for your particular offer and your particular customer. Don't try to hammer a square peg through a round hole if your best, most valuable and likely to convert, customers would rather take their time with a robust desktop experience.

Look at your product or service, look at your customers, and of course, look at your analytics. You might find that 50% or more of the traffic that comes through your door is from mobile devices, but where are your conversions coming from? It always pays to dig a little deeper than to just follow every fad.