It depends entirely on the director.
Some people think skits are only something with interactive dialogue between two or more people, while others think a skit is everything that ISN'T "walk on, pose, walk off, no music or introduction."
I personally don't care, really. Every person who gets up on stage, to me, is doing a "presentation" or "performance." There is no skit versus walk-on in my book, everything belongs in a single "presentation" category. How long that presentation is will be determined by the rules; the content of that presentation is as wide open and interpretable as the imagination of the performers. I also personally find it extremely unfair to force people into one of two camps and deny them awards because they do or don't fall into a certain category, but that's another argument for another day.
The only time it matters is when you're entering a masquerade that clearly, in both rules and awards, delineates between a walk-on and a skit, and in that case, you have to defer to the director. In those cases, if awards for skits are being given to walk-ons, or vice versa, the director would have had final say and if they let these awards stand, then all the arguing and complaining is pointless. Now, if the director doesn't KNOW that awards were given out in the wrong categories, they should be asked or informed politely and allowed to make final decisions. If the masquerade doesn't separate the two, and the only reason people call one thing a skit and one thing a walk-on is their own personal definitions - and there are not strictly separate awards for two categories - then what is or isn't a skit is moot. And then the arguments become REALLY pointless. The audience has no say in what gets awards anyway.
All I know is, when I become director of a masquerade, there will be no such divisions. The only separation I endorse is skill divisions, to protect the novices from the masters.
Founder and President, Madison Area Costuming Society, a chapter of the International Costumer's Guild
Strange Land Costuming - www.strangelandcostumes.com