If you have invested a lot of time or money in SEO or pay per click it is important that you do not stumble at the finish and lose potential business due to technical glitches.
One test I suggest you do regularly is to fill in all the contact forms on your web site. Testing weekly is a recommended. And if you have a shopping cart make sure you do regular end to end tests including testing the payment gateway.
With all the bug fixes and code upgrades that occur invisibly on your web hosting, it is not surprising that the contact and order forms on your web site sometimes break.
This is particularly an issue with WordPress sites.
WordPress now has an auto-upgrade facility. The trouble is your contact forms may not work with the latest WordPress version.
Last year the Internet was abuzz with a warning about a security problem named Heartbleed.
In their mad rush to fix this fault some hosting companies screwed up their clients email gateways. And unless these clients tested their contact forms, there would be no way they would know there was a problem.
I have known of web sites where the contact form was broken for 18 months. The client thought it was an SEO and web traffic issue – in fact it was a web site coding issue. They had no idea because nobody ever tested the request for quote form.