I do not degas particularly, but then again I am pretty relaxed about how much starter I use. Most people here will weigh their starter, if they're being careful about how much to use, so volume doesn't matter much. If you want to be precise, you can either weigh or, I suppose, just follow the same steps every time (stir 10 times, then use 2 tablespoons, or whatever you like).

I never stir my starter up unless I am feeding it, or using it. When I feed it, I stir thoroughly, to get the existing culture and the new flour well mixed.

thanks for your reply. Im sure there is no real way of doing it, though it seems you want to le the starter bubble to its full capacity.