With suitcase you can import entire folders of your font library at a time, you don't have to load each font family individually (this works best when you do NOT have the fonts activate automatically when adding them). Each font set (typeface family) will remain in their individual folder, so it's not like you'll have to go through all 50 weight variations of Helveltica Neue and group them into a set.

However, if you want to further group the fonts -- such as alphabetically (a-l, m-z), by kind (sans serif, handwritten), or by client name -- yes you will need to create a set for each of those groupings. honestly I prefer that because I've found each agency and each designer likes to organize in their own way. I like to organize by foundary, alphabetically grouping them within each. In addition I also make sets by client project so I can quickly activate/deactivate based on the project. Moving a font or family to a set doesn't remove it from it's original source, it just makes a copy like an alias. So you can have the same font in several different sets.

But it's not necessary to make new sets to use suitcase. You can just activate/deactivate the fonts individually.