Most of the plugins are out-of-the-box, easy to install and simple to setup.

I’m sorry to say, this is not the case. Once have installed a WordPress plugin, depending on which one requires some configuration. Some are more simple to configure than others. Also, some of these plugins may require to be stylized to match the layout of your website. Every practitioner could benefit from having a calendar on their website to schedule appointments. Some of these calender plugins are truly UGLY and the colors are off from your brand. So, I recommend being selective of which WordPress plugins you install on WordPress theme. It is important to note, maybe your WordPress theme or website is not compatible with a WordPress plugin, this can cause the entire website to crash or get a warning message.