All the odd cubes (5x5, 7x7, etc) aren't really much more difficult than 3x3. You can learn basically one or two extra algorithms to reduce it to effectively a 3x3 (e.g. for a 5x5 consolidate 3x3 centers and 1x3 edges, then solve exactly like a 3x3). And honestly the consolidation steps are pretty easy to figure out without actual algorithms for the most part.

I never really messed with even cubes (4x4, 6x6, etc) but I'd imagine they scale the same.