Over the Christmas period I was shocked at how often I hit a dead end when trying to place an order with a leading shop on my phone.
Dorothy Perkins' sign up process hit a snag and then timed me out of my session and lost my basket, FeelUnique almost made me hit a deadend when a "continue" button during the checkout process just wouldn't click on my phone (but clicking the link to visit the desktop site got me back on track - a surprising upside to not being a responsive website), and it wasn't the first time I'd had problems checking out of Argos on an iPhone or iPad meaning the order had to wait until I was back on a desktop. (On this occasion I was using an up to date iPhone 6 and Safari.)
All of the websites named here are really good websites in so many ways - and really great online retailers with regards to pricing, selection, or how quickly they deliver. But they did have me cursing at a frantic time of year when I had spent time building my basket just to find I couldn't check out!
If someone wants to give you money - make sure they can
The issues I encountered weren't to do with responsive design; they couldn't be solved by making your browser smaller and seeing how the page looks on a different sized screen. And I really don't know if they could be re-created on an emulator.
Sometimes you just need to test across a lot of devices, because something as simple as a button not being clickable - despite being present and seemingly correct - can stop someone in their tracks, and give a very frustrating user experience. I've been the developer on the end of an issue like this - a few years ago, a landing page I worked on the build with had a button that couldn't be clicked on IE8. Completely obscure and easily solved once it was found - but it could only be found by testing on that specific browser.
Testing is dull and can take a long time - and so is expensive. But if it starts saving you orders, and keeps UX at a high, then it's worth it.
Therefore if you've got a shop and it's had some changes lately or you haven't tested it thorough across a variety of leading smartphones (check your analytics / stats if you want to focus on which devices visit you the most) - get testing! Ideally write yourself a basic test plan - just some notes on what you're testing, what should happen (and then you can fill in what does happen if it's different), and the devices / browsers you're testing on. Remember to consider all user journeys - once you've got a test account it can be too tempting to just test as an existing user but testing that someone new coming to the site can sign up an place an order is vital too.
If you're over stretched and would like us to write a test plan for your website, carry out a UX review or test your site across various devices, please contact us.