if you are not disciplined then you may not be able to manage any website, you have to manage the website according to its requirements, some websites are service website so you have to manage your clients with respect so that you can get good business.
Re: managing a website requires time, disciplines and lots of work
Management of website is not just limited to uploading new content or pages and removing dead content from website. It includes testing of the different functionality of websites and making sure everything working the way you have defined while development and design phase of the website. You should check Optimize website management also include uploading website with its design as well to match the current trends and ongoing event. Uploading Christmas banners in December and giving away special discounts can be added into one step in its management same way your web design must reflect current ongoing event or things.
Re: managing a website requires time, disciplines and lots of work
This is true. Search engines prefer to see frequent updates and loath stale, unattended sites. It's important to keep content fresh and to keep engaging human visitors. This not only helps with optimization, it increases monetization as well.