URL optimization is very important aspect of on page seo, its very useful when you don't have any keyword in domain.
Think as your visitor would it be nice and convenience to have 1-2 clicks to get what they want? There is no magic or secret ... the less is more
there's 2 types of URL, dynamic and static URL Dynamic URL : hxxp://www.randomsite.com/myblog/catid=3&article=5 Static URL : hxxp://www.randomsite.com/cars/veyron-bugatti users likely to click a url in a SE query that matches the title and description than one that doesnt make sense to them.
If any keyword is in url then we can archive high ranking in search engine by the. Domain Structure is most important for seo