To do a topic justice, some vid's do need to be very long.

This is more of a style thing. If the presenter is up front on the length and detail its fine. Many topics do require a long or multi-part video.

Example: A short review video of a gun followed by a second video detailed review. The second video picks up where the short one left off so you don't end up repeating a lot of the same info. Then both types of viewers get what they want. Sometimes I'm only looking for a quick and dirty review but when I'm looking to buy, then I want all the details and opinions I can get.

Other Example: Just about any museum is going to need a detailed review to do it justice. If someone just wants the "where it is/hours open/phone/web page/etc... you put that up front and then continue.

Last is the title can be more informative for the above, if you choose a consistent title method, so users that know your channel, know what "Brief Review" and "Detailed Review" mean on your channel. I believe that more meat on the bone is a good thing. You tube has enough 2 minute video's what are all bone and no meat.

I like your videos or I wouldn't be here. Keep up the good work.