Hopefully, no one knows your business better then you do. You live it, breathe it, it is yours. So logically, the best person to critique your business' website is you, surely? Arguably, no.
Sure, when it comes to the details about service descriptions, price lists and how the business was founded, you'll know best. As for navigation, content, design and many more elements - these things should be defined by the end user. That's not to say that a business owner knows nothing of what their customers want from a website but, until you actually ask, you can never be sure.
Not only does website feedback allow you to improve your website, it can completely change your business operations. For example, finding out that most people who visit your website prefer to pay online rather than over the phone could inspire you to offer online payments thus satisfying more customers and potentially increasing business income.
When to ask for outside feedback
There is never a wrong time to get constructive criticism on your website. If your website is brand, fresh-on-the-server, new then you might think it's too late - the site is built and done - however you can still act upon certain points of feedback like the written content being 'too wordy' or not descriptive enough. Of course, when you've just unveiled a shiny new website the last thing you want to hear is that your end users don't like it but it's better to know than to think otherwise. Yes, it might cost extra to 'change where the menu button is' or to 'get rid of the flashy video because I don't like it', but if doing so results in happier customers, that can only benefit your business long term.
Asking before you start a new website build might be the best time as it allows you to bake the requirements of your customers into the design, but asking at all is the important thing. Even if you've had the same website for 7 years and it's 'doing fine', it can't hurt to reach out and find out what your customers are thinking about it.
Who to ask for website feedback
The more opinions you can get the better. Ask new customers, existing customers, fellow business owners, your dentist, family members and friends. Ultimately you want to build the site for your customers but having as many people offering input as possible is helpful.