There are a lot of variables in regards to how long it takes to write a new hub. Do not expect to sit down, nail it out and have it finished in a half hour, or even an hour. Every person has different skill levels when it comes to writing, spelling, grammar, sentence structure, keyword research and layout design.
Some people might write the hub in a half hour, and then spend hours key word researching. Others might do it the other way. Then there are pictures, videos and so on.
Even when you finish the writing, pictures, design and SEO, don't think you are finished. As you add new hubs you may wish to edit old hubs to link them together. Plus from time to time you go back and edit the hub to keep it fresh.
Time yourself, that is the only way you will know how long creating a quality hub takes.