Well, the more frames you take, the more of them will be mediocre but the proportions should be more or less the same, and by laws of averages you should get more awesome frames
of course, it's entirely possible that you click the record button just as the seeing deteriorates and you get a higher proportion of mediocre ones...
Take a bunch of sequences. Hard disk space is cheap. Good night under the planets, not so much
But also, spend the extra couple of minutes getting the alignment right with your Dob so the object stays closer to centre for longer. Mirrors aren't perfect, especially as they tend to the edges. And you'll be able to take longer sequences with more accurate tracking.
Doesn't matter whether you're using a Dob or an EQ for planetary, so long as it's tracking well....reason being is that the individual frame exposure time is very short - I'm using 15-20ms but it depends on what your camera will support - and in that time there's very little field rotation, or noticeable rotation of the planet in question. I found with Mars though he features do move within a few minutes though, so faster = better if there are high contrast surface features.