The meaningfulness and result of your talk don't depend as much on the time spent on your speech as on its main goal. For example, videos for a YouTube channel should be short, informative, and full of content – think 2-3 minutes.
With master classes, everything is set up completely differently. First of all, the audience can't exceed 20 people; otherwise everything will turn into chaos. Secondly, you have to try and get the audience as physically active as possible. Let the participants mix, taste, and smell. Set up experiments and get people as involved as you can.
Today, many people still have a firm belief that the quality of a talk depends on its length. This is not the case: 45 minutes is more than enough to do something memorable.