I keep mine in an open air container, preferably no more than five days but I have left it in that environment for over 20 days before.
I used to leave it in there around 14 days but decided that probably wasn't the best practice.
After it's gone in the glass container I rack when the yeast has done fermenting the sugars and the mead is sitting on its lees, at least that's what I try to do.
Sometimes fermentstion is sluggish, sometimes I'm lazy or distracted, other times there's no new glass vessel to rack into.
I don't want to leave it on there until it starts smelling funky. I want the lees smelling like fresh baked cookies not onions at the time of racking haha.